Blender Version
Broken: blender 2.8
Worked: blender 2.79

Short description of error
While in texture paint mode with a subdivision modifier on a mesh, hiding faces doesnt work. It only works when the modifier is turned off

Exact steps for others to reproduce the error
-Add a cube with a subdivision modifier.
-switch to texture paint mode and select face selection masking.
-select a face and try to hide it
-disable the modifier in the viewport