I have tried this mod by itself with its dependencies (LW2 Secondaries + New Promotion Screen By Default) in a new game to see if there are any other mods causing problems but all custom made perks are missing from the new classes, and when promoting rookies I am greeted by "Missing 'LocFriendlyName' for ability 'None".

I have also tried refreshing the game by deleting everything in My Games/XCOM 2 WOTC/Xcomgame/config and restarting, but the problem still occurs when starting a new game.

I'm not sure what to try next.