1 other conflicting mod, Genetics Reborn. Whenever Injecting yourself with an infused syringe that involves health, then transforming to say a bat, then back, then bat, then back.... etc will continuously increase your max health. Not sure if this deals with MetaMorph or the other mod conflicting. Hope this can be fixed! Thanks

I don't know how to test a minecraft mod from github, but looking at the code, could the issue with this be in AbstractMorph line 123:
this.lastHealth = target.getMaxHealth();

Should this instead be:
this.lastHealth = target.getHealth();

?