Chairmanwon’s g17 v3 problems

Hello,
I printed the engraved V3 frame then added lone wolf's lower parts kit a LEO precision Oden slide and Wojtek's rails to complete it.
Initially the rails fit perfectly but the slide was very tight so I used diamond lapping compound to fix that.
However when I went to fire it it it would be essentially single shot with the OEM 17rd mags I bought and if it would eject it would eject straight at the operator's head.
Running some snap caps through it by hand I noticed that the top round in the magazine would jam on the fired casing when the slide would move about .25" back and stop any further movement. If the mag is empty or dropped the round ejects fine. Has anyone else encountered this problem? I'd prefer not to have to re-print it but don't see what else to do.