I just had a game, where the predator jumped between a rock and tree just by the exfil at NW in Overgrowth, then engaged the self destruct. When I went to defure, my character was apparently still falling between the rock and tree, but there was no ground to land on.
This resulted in a weird bug, where the defuse combination selector would change as if I had W or S pressed down (when I did not). I had to cancel, re-enter the crevace between the rock and tree and this time it seemed to land and I could defuse normally.