Operating system: Darwin-18.7.0-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro 560X OpenGL Engine ATI Technologies Inc. 4.1 ATI-2.11.20
Broken: version: 2.81 (sub 12), branch: master, commit date: 2019-09-29 21:43, hash: rBff10ff782bde
Short description of error
It took me a while to figure out why objects aren't showing masks in Sculpt Mode. After I created a new object and painted with mask it showed. Then I decided to apply the bevel or subsurface modifier and the mask appeared on the object normally. It's not a problem with the toggle.
Exact steps for others to reproduce the error
Add a cube, a bevel modifier and try to paint it with a mask on sculpt mode. It doesn't show. Apply the modifier and it starts to show again. It also doesn't show on Armatures, Subsurface etc.