I've seen this happen a ton of times, and its super frustrating. I'm not sure whats causing it, but my group has had multiple things happen automatically without any input from the user.
Examples:
First turn in combat, your character will move to a location without your input. (This could be where they were going to move before they entered combat, but I'm not sure.)
I've also seen characters enter stealth immediately at the start of their turn, usually the first turn, but without user input.
This one is the most painful, sometimes after using a resurrection scroll in the middle of combat, and putting the player where you want, they will res. there, but then they will INSTANTLY move to some other spot, likely walking directly through some hazardous ground surface.
I'm not sure what's causing this, but its super frustrating to constantly be losing AP to this.