I’m not sure if this is a bug, but this behavior occurs occasionally to me and I have no clue, what causes it. Sometimes the snap cube stops working. If I tap on it, nothing happens. Hitting the snap-icon still does the job, but the cube is taking five. Sometimes it goes back to normal, sometimes I have to restart. I have no clue, what is causing what. The only thing I can tell: When it happens I see a red dot on the screen the moment I touch it:
Here the dot appears next to the gizmo on the left side + this is not the spot, where I’m touching the screen.
I just checked and now it’s working again. I cancelled an autosave. Right after that, the snap cube was back on. Before that - nothing.