I'm using Pixie's combat library for my game and everythings running pretty smoothly, save for the hitpoints. Health potions don't increase health, and I can't make any scripts that change health. As far as I know, I haven't touched anything that could make this happen, it just started up when I first tried using a health potion.
Bonus points if you can tell me how to increase maximum player hitpoints using scripts!

first, make sure you toggled on the built-in 'health' Integer Attribute and all of quest's underneath handling of it:

'game' Game Settings Object -> 'Features' Tab -> the 'health' check box -> check it in

if it's still not working... Pixie will have to help you with it

Healing potions work okay for me. Are these standard potions , set up by selecting "healing potion" from the Combat tab?

It might be worth clicking on Debugger during play, and check what the player hitpoints attribute is before and after taking the potion. Bear in mind the player cannot be healing above the maximum (40 + 10 x stamina).

One thing to be aware of: The GUI has two functions, "Increase health" and "Decrease health"; these are for the built-in health system, which uses an attribute called "health". My combat library uses "hitpoints", so they will not work.

To change the maximum hits, you need to override the CalcFullHits function.