Talking to Smith-Wesson once floorplate is on the 45 7 round magazine and pushed all the way back. The prongs are to be pushed backwards and they will retract into the floorplate due to the pressure from the spring. They slide back into the grooves.
I had one of two with the reassembly problem.
Then troubleshooting the issue on the other one ended up with the same problem. So now I have two magazines not useable. While talking to support one actually sprung back, really surprised me when it happened.
I also had a slide release problem with the 45 Shield in which two hands could not get the slide release to work and had to send it back. So I iincluded all the magazines. Before I boxed them, that second one snapped back in place, but this shouldn't be so hard for cleaning etc..
I also had hard time getting more than 3 rounds into those magazines without my UPLULA, very stiff springs. Never had this much trouble with rounds except for the last 1 or2 rounds.
But this is what I found to share.