I'd just back the over travel screw out a 1/4 of a turn and see if that made any difference. It is possible to have the over travel set too close. The rifle will fire because there is the power of the compressed firing pin spring over it. But, when you go to withdraw the bolt, the sear hasn't enough room to depress, because the trigger is in the way and blocked by its over travel adjustment screw, to allow the bolt smooth movement. In my 30+yrs of 'bench experience' I've seen that more then just a few times. The makers of aftermarket triggers might call them "drop-in", but they need to be properly adjusted, too. If that doesn't work, then I'd put the OEM trigger back on and see what difference that would make.