Operating system: Linux-4.18.0-25-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 670MX/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.116
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-02 12:17, hash: rB163996b68129
Short description of error
When you are in sculpt mode and you turn on the face orientation overlay, and then you sculpt, in the places where de brush make contact with the object, the blue color go away.
Exact steps for others to reproduce the error
In sculpt mode, active the face orientation overlay, sculpt and see the result