System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-05-31 21:28, hash: rBfcccee0c3372

Also broken at least in 2.82.

Worked: no idea.

Short description of error
When a model has a particle system (like my face has beard), the sculpt mask is invisible (but it does work).

Exact steps for others to reproduce the error

1. Open the attached sculpt_mask_invisible.blend
2. Select the head model
3. Go to sculpt mode
4. Select paint mask tool and paint on the face
5. See how the black mask indicator does no appear (but the mask still works)