I have a shower door that is metal with a class center. it will not stay shut. I have tried applying magnetic tape but this "metal" did not catch.
Did it ever work properly? I would look for a round medium strength magnet and glue it to the door at the top or bottom (or maybe both). Of course, I'm assuming that it is supposed to hit a metallic rail at the top or bottom that it's supposed to stick to?
Are you having a framed shower door? That's the common problem that most people really encounter with a framed shower door. And having the right specs for repair is so hard to find. I would suggest you upgrade your shower area with a rather frameless door because it is more convenient. Trust me it works fine and easy.