Unble to split sence/antisense pair on two

[AlexeyGirin]

Steps to Reproduce

1. Go to Macro - Sequence mode (clean canvas)
2. Load from HELM: RNA1{R(C)P.R(A)}|RNA2{R(G)P.R(U)}$RNA2,RNA1,5:pair-5:pair|RNA1,RNA2,2:pair-2:pair$$$V2.0
   
3. Switch to Edit mode, click in the middle and press Enter key
   

Actual behavior
Nothing happens.
System starts new sequence

Expected behavior
System splits sense/antisense chain pair on two

Versions

• Ketcher Version 3.1.0-rc.1 Build at 2025-02-04; 21:27:02
• Indigo Version 1.29.0-rc.1.0-g2e30df8f7-wasm32-wasm-clang-19.0.0
• Chrome Version 133.0.6943.54 (Official Build) (64-bit)
• Win10

Issue found while testing: #5942