Quote Originally Posted by Bill Burk View Post
I have a theory that fits this.

The film didn't catch the takeup spool when first loaded... but after some 20-or-so shots, it FINALLY caught and started winding...

So it might have been good to go, but OP rewound and sent the film in for processing.

All good advice to check the wind knob is turning as the shooting progresses. Good to check that the camera can make it through a roll of scrap film when properly loaded... But chances are... Next time you shoot... You'll get a good roll of film.
That's the same thing I was thinking. It's easy to have the film pop out of the take-up spool. I keep my "36 frames on the leader"-oops roll around as a warning for the future, the film equivalent of Cromwell's head on a pole. I should probably cut and sleeve it, put it in an 8x10 frame and hang it on the wall.