Hello and thanks again for your feedback and kind words!
I'm not sure what causes you bug with "Buy Max", but I'll look into it.
I've already moved the buy all button for leveling your cats below Manny, the cat in the middle. It's also a little bigger. This change will come with the next update, together with other, smaller changes to the UI.
About the "Buy all button", that you get for Favors: I think the best solution is to make this a permanent upgrade, so it won't get reset, once you've bought it. I'll work on it as soon as it can. :)
Thanks again, feedback like this is what improves the game's quality and gives me more incentive to put even more love into this and other projects.
Have fun and stay healthy!