Board Thread:Bug Report/@comment-31476236-20170322141852/@comment-3509554-20170324052733

I have some theories for that issue.

1) You are playing on Action Mode, change the game mode on the mod options, in the main menu, if even after changing Action Mode still bother you, go in the mod save folder and delete the config file.

2) You are playing on Capped Mode, where your character level is capped to the biome level or toughest monster nearby, but that doesn't explains why you can't place First Aid skill in the skill slot.