They are all lvl 5 Luna is lvl 10 as they're all on max affection also but Lucy is on lvl 4 as it says make a relationship with the other girls still, I think it's a bug/glitch.
Yep 100% bug/glitch re did the entire game an it works now, I think it's because if you meet the cat guy first it won't allow you too continue, or it's a galley glitch since I saw it for a split second till it glitched back too one of the other galleries.
Don't think its meeting the cat guy, I had maxed all girls aswell and didnt work luckly i had a save were rebecca only needed 1 level and worked after.
My guess the quest checks for a relationship increase after, instead of meeting requirements.