No health & health bar in ATM3 world

I’ve a bit of a problem with one of my ATM3 worlds. There is no health bar and I also die anytime I take damage. it’s only happening in one world and new survival worlds work fine. The world it happens on was moved after I reinstalled FTB on an new operating system (win 10). It was previously running on a different OS with a different, older java installation. This is what it looks like:

What is going on here? How can I get my health back?

EDIT: I checked with armor and armor does show up normally above where the health bar should be…