I don't know enough about the internal formatting of the SYX files saved by FactorLib, or exactly what the PF is expecting to see there, to know whether or not recreating the presets is the only solution. I mean, they look simple enough (text files, it appears), but I don't know if there may be a missing or extraneous space or tab or something that might cause something like this, you know? Maybe Eventide will be able to shed some light on this on Monday.
I do know that I recreated my presets after updating and haven't had any problems. I did that because I knew there had been some changes to the ranges available with some parameters and thought it was a good opportunity to further refine my sounds. It was slightly time consuming (I started with 42 presets and wrote a few more along the way), but it wasn't too bad, either, and I got to explore the new changes and found some new sounds. I can certainly commiserate if you do decide to rebuild… Hopefully, someone else has had a similar experience and can offer a better solution, though. Good luck!!