Lost S-group

**Steps to Reproduce**
1. Unzip the file to get cdx file
2. Go to demo version of ketcher
3. Click on Open, then Open from File
4. Use the file (unzip first): [20251215_formula IVc.cdx.zip](https://github.com/user-attachments/files/24501441/20251215_formula.IVc.cdx.zip)

5. Observe the canvas and compare chemical rendered VS chemical in the original cdx file

**Actual behavior**
Internal s-group is lost

**Expected behavior**
Both internal and external S-groups are preserved

**Screenshots**

CDX (ChemDraw)

Ketcher

Desktop:
- OS: MacOS 15.6.1 (24G90)
- Browser: chrome
- Version: 142.0.7444.176

Ketcher version:
Version 3.12.0-rc.1