HDMI monitor attached via Lenovo ThinkPad Thunderbolt Dock 4 not showng any image despite being recognized (not reproducible on Windows)

[rugk]

I have the following hardware:

• Framework 12 laptop
• ThinkPad Thunderbolt 4 Dock (USB-C)
• Elzo Nanano Cooperation 24'' monitor attached via HDMI to said dock

problem

It is shown in GNOME monitors as a monitor:

However, it always gets no signal.
Everything else with that dock works.

tested things/tried/problems excluded

• The same setup with a different Windows device for testing works and shows the monitor, so no hardware problem I guess
• I updated the firmware of the Lenovo dock to the latest one (v10.19) using fwupd respectively the Firmware GNOME tool
• when I attach the monitor via HDMI directly to the Framework 12 laptop, it also works flawlessly

Questions

So what's the problem here? The dock? How to troubleshoot further?

fwupdmgr

$ LANG=en fwupdmgr get-devices
Framework Laptop 12 (13th Gen Intel Core)
?
??13th Gen Intel Core? i5-1334U:
?     Device ID:          4bde70ba4e39b28f9eab1628f9dd6e6244c03027
?     Current version:    0x00006134
?     GUIDs:              c3f97ae6-7da2-54cc-ad26-3225f9517203 ? CPUID\PRO_0&FAM_06&MOD_BA
?                         cd7d026a-65a8-597d-a73f-b856af9dc9e2 ? CPUID\PRO_0&FAM_06&MOD_BA&STP_3
?     Device Flags:       ? Internal device
?   
??BOE CQ:
?     Device ID:          aec1a869eb0df71b7cea6b3ac71d39b830faf164
?     Vendor:             PNP:BOE
?     GUID:               8fb51768-3e07-5304-a288-0d59020fc1ee ? DRM\VEN_BOE&DEV_0D56
?   
??HDMI Expansion Card:
?     Device ID:          ff75e69eba7f7bc73bf2e2524de4c41d32d61506
?     Current version:    3.0.16.106
?     Bootloader Version: 3.0.2.900
?     Vendor:             Framework (USB:0x32AC)
?     Serial Number:      11AD1D000417330B320B0B00
?     GUIDs:              ff59aed5-f8a7-5742-901a-1876d48ea0b5 ? USB\VID_32AC&PID_0002
?                         7cffc965-2ead-5c70-bd62-ce81a42d37fc ? USB\VID_32AC&PID_0002&MODE_FW2
?     Device Flags:       ? Updatable
?                         ? Device stages updates
?                         ? Unsigned Payload
?                         ? Can tag for emulation
?   
****snip***
?   
??ThinkPad Thunderbolt 4 Dock:
? ?   Device ID:          1c6964271d721d56d725a50a644b50da941c66c0
? ?   Current version:    10.19
? ?   Vendor:             Lenovo (USB:0x17EF)
? ?   Serial Number:      1S40B0ZDHQ6PT4
? ?   GUIDs:              8d30b09f-bcc5-5379-bc65-9ccceeece1f4 ? USB\VID_17EF&PID_30B4
? ?                       275e4695-9b4e-5263-835e-8681bec8cd1a ? USB\VID_17EF&PID_30B4&CID_40B0
? ?                       fe1be6a9-3027-5135-8e1b-737015e2b5dd ? USB\VID_17EF&PID_30B4&CID_40B0&REV_0042
? ?   Device Flags:       ? Updatable
? ?                       ? System requires external power source
? ?                       ? Supported on remote server
? ?                       ? Device stages updates
? ?                       ? Signed Payload
? ?                       ? Can tag for emulation
? ?   Device Requests:    ? Message
? ? 
? ??Dock Management Controller Information:
? ?     Device ID:        e5b3d65de07a7c17606684cc6f1f18c027ad99d4
? ?     Current version:  10.19
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     Serial Number:    1S40B0ZDHQ6PT4
? ?     GUID:             697a6a95-464e-5b90-a46e-73beab89316e ? USB\VID_17EF&PID_30B5
? ?     Device Flags:     ? Can tag for emulation
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Audio Controller):
? ?     Device ID:        0eb6ab10297e58fe25abd78910b73d3a8d4552e2
? ?     Current version:  49-0E-41
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             e1443fec-2b49-5bd0-b921-662ed11e88df ? USB\VID_17EF&PID_30B4&CID_AUDIO
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Display Port 5):
? ?     Device ID:        3f1b7f296e16fdb2bcbc8a572d51f2bcc0c376c5
? ?     Current version:  5.07.008
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             755e347f-4ae7-53f8-ad69-45b3e9145ed8 ? USB\VID_17EF&PID_30B4&CID_DP5x
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Display Port 6):
? ?     Device ID:        cd7818b548cf9ad274b9e769fcd08bb77d53e414
? ?     Current version:  6.05.007
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             a7b49eae-1c1d-5b83-ac90-9bbe78ee39c1 ? USB\VID_17EF&PID_30B4&CID_DP6x
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Dock Management Controller):
? ?     Device ID:        2a52b7bf5c036e190e689d25f0231664588837ee
? ?     Current version:  0.1.103
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             3edd934f-9800-59c9-b02a-11be480d72e5 ? USB\VID_17EF&PID_30B4&CID_DMC
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Dock Management Controller):
? ?     Device ID:        30c18bbb5b12c5c1a25ce3898602d966664ad446
? ?     Current version:  21.20
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             c287973a-cc6b-5d2a-ac71-3956a512f73d ? USB\VID_17EF&PID_30B4&CID_MCU
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Ethernet Adapter):
? ?     Device ID:        bc04ab7ffc90e9f68925d602e57befa8303f9b6c
? ?     Current version:  1.148.255
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             abbc9b3e-43fe-538f-bfaf-b7e74b3fd47c ? USB\VID_17EF&PID_30B4&CID_I255
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Power Delivery):
? ?     Device ID:        5f2f301e6e44896c46477ac4c55ef04be98596fc
? ?     Current version:  12.5.57
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             e83aba6c-99b3-5e87-b982-ba57a1bf750f ? USB\VID_17EF&PID_30B4&CID_PD
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (Thunderbolt 4 Controller):
? ?     Device ID:        0cefcc6128921f21c6ddc0b4b055f50238002900
? ?     Current version:  44.83.06
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             d6408693-09a5-5f0f-b492-275b5ed16d10 ? USB\VID_17EF&PID_30B4&CID_TBT4
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (USB 2 Hub):
? ?     Device ID:        4ea0056aecc2b53a588b2cbc2b24f20039830dd5
? ?     Current version:  V1003
? ?     Vendor:           Lenovo (USB:0x17EF)
? ?     GUID:             4eab6a92-0ec3-5221-ac0b-c841655f7989 ? USB\VID_17EF&PID_30B4&CID_USB2
? ?     Device Flags:     ? System requires external power source
? ?   
? ??ThinkPad Thunderbolt 4 Dock (USB 3 Hub):
?       Device ID:        ee36bcd95125ff075b398904e4433e6e58274c2c
?       Current version:  5563
?       Vendor:           Lenovo (USB:0x17EF)
?       GUID:             0e5b868b-34a4-5753-8f2e-fe5326494d7a ? USB\VID_17EF&PID_30B4&CID_USB3
?       Device Flags:     ? System requires external power source
?     
??ThinkPad Universal ThunderBolt 4 Dock:
?     Device ID:          2d9bd19a73af0e1160733d42c55f1d9de90ed451
?     Summary:            Multi-stream transport device
?     Current version:    5.07.08
?     Vendor:             Synaptics (DRM_DP_AUX_DEV:0x06CB)
?     GUIDs:              64bb94bb-f920-554d-b7e2-a15650c737f5 ? MST-602
?                         31e8159f-213f-5259-9790-a33948412eed ? MST-dock-602
?                         7c84183b-41f0-5259-83c0-77ba5db0f034 ? MST-dock-vmm5332-602
?                         2a45c6cf-3641-50ec-9f69-4ee875d0d1ff ? MST-panamera-vmm5332-602
?                         845c1ee2-4291-5086-b04d-9f011808e75a ? MST-panamera-602
?     Device Flags:       ? Updatable
?                         ? Device stages updates
?                         ? Unsigned Payload
?                         ? Can tag for emulation
?     Device Requests:    ? Message

System

$ rpm-ostree status -b                           
State: idle
AutomaticUpdates: stage; rpm-ostreed-automatic.timer: inactive
BootedDeployment:
● ostree-image-signed:docker://ghcr.io/ublue-os/bluefin-dx:stable
                   Digest: sha256:7b7cc6bf35a1e4d26c50d588784fb208bbeb465adfa352e1509a3c01b7ec8271
                  Version: 44.20260623 (2026-06-23T01:58:39Z)
      RemovedBasePackages: code 1.125.1-1781859648.el8
$