If your yoke screw doesn't have a spring loaded plunger in it, one of two things has happened. The yoke screw was a fitted part, so either:
1. You mixed up the screws when you, or a previous owner, had the side plate off. Easy fix, try installing the middle side plate screw in the yoke hole and see if things are different. DON'T use a thread locker.
2. Someone at the factory didn't properly fit the yoke screw. There's a couple of retired armorers here who can provide further instructions on fitting if that's the problem.
Added edit: Come to think of it, there is a third possibility: a previous person lost the correct screw and bought & installed a new one not knowing it's a fitted part. Also, somewhere there's a thread on how to fit yoke screw.