In my haste to fix the [url=https://www.nexusmods.com/repellafella/mods/1]Cheevo mod[/url] in Update #4, [i][url=https://www.youtube.com/watch?v=vSY3LCZt70Y]I f&$ked up[/url][/i]. I ended up breaking every achievement by not including the Steam DLL files.
However, that's fixed now. All achievements should be working again in the base game and with the mod. My apologies!