Ibaraki's partner quest, "Can you hold your Liquor?" contains a bug that loops back to the beginning of the dialog despite the option chosen.

The bug is illustrated in this video : https://www.youtube.com/watch?v=Z4VbMC6Y8bI

Edit : Forgot to change from private to Unlisted. Sorry about that. ;^)
Edit 2 : Problem is now resolved with the 5/20/2015 patch. Thank you to Extraordinary for the post.

After last night's maintenance I've had this bug in every single dialog option I've encountered thus far with the exception of Sheryl's initial quest. I hope it gets fixed soon.

I'v just found this and it seems to be with all the NPCs. hope the dev's can fix it soon.

Confirmed in Kyoto. After the maintenance, NPCs encountered requiring a dialogue selection starts an infinite loop of being unable to select any option.

Yeah, my friend and I have been having the same issue. I really hope this is fixed soon, my waifu isn't going to level herself up...

Thanks for all the additional information, guys. Great finds.
Yeah, really hope they fix these issues soon. ;/