Under the processing lever is a metal arm that operates the catch which holds the negative in place when you pull out the sleeve. With the holder out of the camera, you can press the arm and make sure the catch moves. It's a pretty simple mechanism, and not too prone to failing, but if it's dirty, then it may not retract enough to release the negative when you pull it for processing. Another problem is that the metal edge on the film pack may be bent or distorted which will cause this as well.
If I remember correctly, development time is 1 minute, but I think it's self limiting, so within reason additional time may not matter much