Yeah, this seems to be some kind of trend, that each update ia only somewhat compatible with save files from previous versions, although most of the times clearing game cache helps.
As for the relationship thing - this is not a bug, that's deliberate and makes it a little harder to earn relationship levels, there's a "lock" on lvl 20 and 40 (60 and 80 are WIP) - it's best to talk with Yuna just before you start the night to get a hint as to what needs to be done in order to progress (if you want a more direct hint, check out changelog on our wiki)
Cheers