Hi fellow players,
it appears there is a glitch concerning Joy, you seem to be able to upgrade her skills to level 55 instead of the usual 50 now.
I've already posted to support and I think this issue will be resolved soon, so it isn't even worth doing it. However, if you still try to level her up, be careful: When I tried that, it let me level up the skill to supposed level 56, which reset my skill to level 1 and now appears to have to be levelled up as usual, spending all materials and rupees again...
If you want to help resolve this issue fast, you can also post to support (include screenshots).
Have a nice day,
Edit: The issue is now resolved by downloading the current update. :)