Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: AMD Radeon RX 5700 XT ATI Technologies Inc. 4.5.13587 Core Profile Context 20.4.2 26.20.15029.27017
Broken: version: 2.83.5, branch: master, commit date: 2020-08-19 06:07, hash: `rBc2b144df395f`
Worked: Before face sets implementation
**Short description of error**
When sculpting with dyntopo if you undo sometimes part of the mesh simply dissappear.
**Exact steps for others to reproduce the error**
-start sculpting with any primitives using dyntopo.
I can't get this consistently, I get this "randomly", but don't think its that hard to happen.
You can make the geometry re-appear by leaving sculpt mode. Once you go back, note that the geometry that was hidden is now a face set.
I think it may be related to https://developer.blender.org/T74637