Raspberry Pi Compute Module 4 question with Bluetooth Add Device...

[bigbearishappy]

I use my Raspberry Pi Compute Module 4(CM4) with the Raspberry Pi Compute Module 4 IO Board.
When I power on the board and use the VNC to control the Destop of CM4.
The bluetooth is turned on by default.
I click the bluetooth icon on the right top of the desktop.Then click the button "Add Device..."
It show me a new dialog of the Bluetooth devices.
However, there is nothing listed in the dialog.
I tried to do something with this.Then I use the "bluetoothctl" and inpu the "scan on"
After a few seconds,the dialog fill with many bluetooth devices.

With this operation,bluetooth works fine when the next time I click the "Add Device.."
Even I turn off the bluetooth and turn on.It works fine.

I tried to find out the difference of them.The only difference is the status of "Discovering"(bluetoothctl->show).
When it works fine,The status of Discovering" can auto change to yes after the click operation on the "Add Device...".

PS:
my OS information:
I use the official image download from:https://www.raspberrypi.org/software/op ... -os-32-bit

uname -a
Linux raspberrypi 5.10.17-v7l+ #1414 SMP Fri Apr 30 13:20:47 BST 2021 armv7l GNU/Linux

cat /etc/rpi-issue
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, dcfd74d7d1fa293065ac6d565711e9ff891fe2b8, stage4

vcgencmd version
Apr 30 2021 13:45:52
Copyright (c) 2012 Broadcom
version d7f29d96450abfc77cd6cf011af1faf1e03e5e56 (clean) (release) (start)

Is there anyone can help me with some suggestion?