@Cat Groove I apologize for the very late answer, but it is likely a case of the mod being overwritten by something else modifying the same files, most likely the defines.lua file of the base game being used as a whole by another mod and thus overwriting this mod's changes to the lines in defines.lua.
I'm not sure the mod load order is a thing for EU4, perhaps if this mod is listed either last, below any other mods, or first, above other mods, but in the case that doesn't work, you could make this mod's changes to the "offending" mod's defines.lua, which can be edited with any text file editor.

Any idea how I can get this mod working again?