Very slow first iPhone and iPad photo sync over usb-a with Catalina
I updated to Catalina last night on my iMac. Today I've tried synching my iPhone Xr and my iPad Pro via USB/Finder (separately) to my iMac and the synch is very very slow. The iPhone never finished after a few hours and I'm trying my iPad now but I don't see any progress in the changes I had made to the photos (I deleted some before I synched, but the deleted ones still show on my iPad). I do have several thousand photos. Is the Photo Cache being rebuilt or something? Should I delete that and start again? Should I sync one photo folder at a time to start with? Is there anything else I should try? Previously I had posted issues with the latest iTunes in this thread:
https://discussions.apple.com/thread/250270137
and solved that by using an older version of iTunes. I would hate to think that Catalina will be as problematic as iTunes for synching photos was before. Any help/advice would be appreciated, thank you.
iPhone XR