Never had any issues with loading 15 rounds in the pro. I carry a hellcat and a hellcat pro, and train with both every range trip. Never had any problems with any of the mags and I have 5 of the pro mags and atleast 4 of the 11/13 round hellcat mags. Idk if you had tried all of the magazines, but I'd start with that . Maybe you got one with a funny follower or spring. My Springfield prodigy does the same thing with the 20round mag. 17 round mag loads easily , 20 rounder needs a big strong 💪 push in to seat. I always load 19 but I don't carry that one so max capacity isn't so important. Good luck