My new to me g29 locked back the slide on the last round of the first mag and then would not release. Looking closer I saw that the slide release was not even up in the notch. So mag or no mag the slide is locked back but not by the lock. Only tapping on the back of the slide (maybe hard) would get it closed. Why is this happening? I looked closely at my 30 and everything looks the same. What's fubared?