Hello 3ds Max devs.
I found an issue in the Unwrap modifier. The issue exists in 2023, 2024, and 2025 3ds Max versions.
Steps to reproduce:
1. Create a box
2. Convert to poly
3. Select any edges and create a chamfer with 0 segments (flat chamfer)
4. Add Unwrap modifier
5. Use the Flatten tool to create some UV projection.
6. Run polyop.CollapseDeadStructs $
After collapsing dead structures, Unwrap will reset all changes. It happens only when it has dead faces (chamfer with 0 segments creates dead faces). Unwrap doesn't reset UV if I collapse dead vertices/edges.
The reason why I collapse dead structures is simple - many scripted algorithms fail if an object has dead subobjects.
Please consider fixing the issue if it's technically possible. Thanks.
