I have a 4536 (compact, SIG decocker) with one mag that has yellow follower and just ordered another mag. This one has a black follower... The problem when the black follwer mag is used, after the last bullet is consumed, the slide stays open. The problem is, the magazine will NOT come out. There appears to be part of the spring visible inside the mag is catching on the slide release. The mag with yellow follower doesn't have that problem. Any solutions?

The magazine spring may be installed upside down. Try disassembling the magazine and turning the magazine spring upside down then re-assemble. Clean and lightly oil the spring, follower and the inside of the magazine body while you have it apart.
Ryon

Thanks, did it and it looks just like my other mag. Thanks again.

Did it resolve the problem?
Ryon