Not sculpting in official 2.79 64 bit?

OK, first time I seen this and not sure what’s going on. Sometimes blender will sculpt and other times it won’t. Like one time I had the default draw brush using dyntopo, it worked for a minute and then the next minute it wouldn’t do anything. Yet you click on display wire and it was adding new vertices ,but it wouldn’t raise or lower the mesh like it should. Anybody can explain this?

Object scale?

Doubt it, it happens adding cube and trying to sculpt on it.

might have figured this out. I turned my pressure/strength to 0 and was able to recreate my issue. I don’t remember messing with my pressure ,but I guess it got changed.