It could be a glitch on your pc? I mean, there are gonna be some smaller issues but I am sure that they are gonna be addressed in the next major installment. I personally haven't played with the new patches yet, but I have heard a lot of the major bugs have been fixed.
It would be a mac in my case but unlikely, as when I emulated the previous version on it the hot-spring trick worked for Leah too. Might try a fresh download to see if it's just on my end, but I'm not getting actual errors so the game is probably just not properly setting the correct flag when changing costumes.
Wait. You're talking about the spring in the fairy forest right? Of that's the case, then people have reported that one. My issue was that there are specific dialog from the last update that never showed up in this update, as I thought it was glitch. The previous dialog from the last game made it immersive in my personal opinion, or the choice of having different dialog coming from different characters; instead of ignoring the obvious. I found that very interesting, which is why I like the series.