My (3) sigma sw9ve magazines won't let the slide stay locked back when empty. They're all brand new factory magazines with less than 32 rounds through each and have been thoroughly cleaned after each use. I used zero oil when cleaning them but wiped them down thoroughly and reassembled properly. Is this a common issue? It happened uring my range session today which is pretty frustrating. Even when it's empty and I'm manually racking the slide it just goes back forward without locking back. Any advice or suggestions are appreciated!