Many "UV island" style operations internally use #UvElementMap, including:
- Transform tools
- Smart-Stitch
- UV Pinch, UV Grab and UV Relax sculpt tools.
Normally, every UV in the mesh is included in the #UvElementMap.
However, with hidden geometry, only the visible geometry is included in the map. [0]
This change enforces stricter usage, reducing the chance of crashes in other areas.
Regression from [0] which was a fix for "UV Island calculation doesn't ignore hidden faces" [1].
[0]: 8f543a73ab
[1]: #99659
Pull Request: https://projects.blender.org/blender/blender/pulls/108130
ae9ac99d2b