System Information
Operating system: Mac OS Catalina
Graphics card: NVIDIA GeForce GT 750M
Blender Version
Broken: 2.81 Beta, eba4a4bd73ba, 2019-11-15, as found on the splash screen)
Wight painting not working
Exact steps for others to reproduce the error
Open this file
In object mode:
Select the rig and shift click select mesh
Enter weight paint mode
Control left click on a new bone
The blue weight paint disappears from the mesh