I don’t know if anyone else has experienced this since the last patch, but for me, on the map Trainyard when as an Attacker I pass by the first objective point it automatically starts arming C4, and I also can’t move or quit the arming. I get locked into position till I’m killed or the C4 is armed.
Trainyard - First Objective - Auto starts arming of C4 with no button push
Temporary1
(Temporary)
#2
I’ve had that but it happened when I was using my primary fire button, very annoying when I’m trying to kill someone by ducking in and out of cover which happened to be the objective on both trainyard and terminal - Wasn’t sure if anyone else had that happen but glad I’m not going insane 
Borganism
(Borganism)
#3
I had this happen to me a couple of days ago. Playing as bushwhacker and I was about to duck into the corner to set c4 and it started auto setting while I was exposed.