Press fit bottom bracket causing bearings to bind
What you're describing is common. One clue as to whether it's necessarily an issue depends on how a new bearing feels and lasts/performs. Press fits always take up some amount of internal clearance and so having some degree of what you describe on a worn bearing isn't necessarily a big deal. But if a new DS bearing behaves similarly, yes that's a problem.

To diagnose something like this, always take a bunch of measurements of the shell bore at different places to see if it's consistent or if the interference fit is greater than it should be. The PF30 standard is open and there's a technical paper for it out there somewhere that shows what these numbers should look like.

PF30 reamer/facers do exist and I daresay anyone selling cdale mtbs should have one. That should fix it better than new, although I don't know Cannondale's take on them on their carbon frames.