SYNC mode button is absent if sense/antisense chain pasted from clipboard

[AlexeyGirin]

Steps to Reproduce

1. Go to Macro - Sequence mode (clean canvas)
2. Paste from clipboard (e.g. press Ctrl+v) following helm HELM: RNA1{R(A)P.R(A)P.R(A)}|RNA2{R(U)P.R(U)P.R(U)}$RNA1,RNA2,8:pair-2:pair|RNA1,RNA2,5:pair-5:pair|RNA1,RNA2,2:pair-8:pair$$$V2.0

Actual behavior
SYNC mode button is absent

Expected behavior
SYNC mode button is present

As per requirement:

4.2. When a double stranded sequence is created (loaded from a file, pasted, or created using the "Create RNA/DNA Antisense Strand" icon #6252) the sync/non-sync switcher should appear and be toggled on by default.

Versions

• Ketcher Version 3.2.0-rc.4 Build at 2025-03-25; 16:50:39
• Indigo Version 1.30.0-rc.4.0-g552c98211-wasm32-wasm-clang-19.0.0
• Chrome Version 134.0.6998.178 (Official Build) (64-bit)
• Win10

Issue found while testing: #6254

[OlgaTitovaEPAM]

Reproduced on:
Ketcher Version: 3.7.0-rc.1
OS: MacOs Sequoia Version 15.6
Browser : Chrome Version 139.0.7258.128
Indigo version 1.35.0-rc.1.0

[zefiris87]

ChatGPT couldn't reproduce it, but it's a false positive - the issue is still reproducible

Ketcher Version 3.11.0-rc.2
Indigo Version 1.38.0-rc.2.0

https://chatgpt.com/share/6938429a-bbf0-8008-bb0a-52cb0b8be075