I have a trigger to do command-H when the mouse enters the top right corner. It sometimes gets in a state that doesn't work consistently or at all. Restarting BBT doesn't help. Saving a small change to the trigger sometimes helps temporarily.
I have the trigger configured to show the HUD when activated and in the failure case, no HUD is shown, so I think it's that the trigger isn't activating even when the mouse is in the top right corner. I have no system Hot Corner configured for that corner (but do for the others) and have no other app that I know of that might be conflicting with it.
BTT 3.346 (1.554), macOS 10.14.6, 3.4 GHz Late 2012 i7 iMac, Trackpad