Seems I recall a similar problem with a certain .243 I have. It would drop the case before it was time to launch it out the side port. It was especially annoying with Federal brass.

I looked at the extractor & compared it to 6 others I had in my spare parts stash. The grabber on the extractor was a little thinner ( as in not as wide) than other ones I had. After a quick change out the problem went away.
I think if it was me, I'd look at the extractor before adjusting magazine feed lips. Maybe QC wasn't exactly Job 1 when they were made?....
Just my $0.02 from a similar situation.