I was having a hell of a time this morning with Blender. I couldn’t get the Texture Painting to work. I searched online for a solution, but every answer seemed geared to someone just learning.
After struggling and not finding the answer online, I finally figure it out. The object I was trying to paint was in the “Local” mode. The local mode quickly isolates one more objects. It is toggled on and off with the “/” Forward Slash key on the keypad.
I toggled local mode off and texture painting magically worked again.