In my latest full play-through (fifth round), I decided to take Potent Cantrip on every character in my party.
a) Game Version: 0.4.21 - Public
b) New Game: started last week
----Paladin-Motherland (High Elf)
----Cleric-War (Hill Dwarf)
----Rogue-Shadowcaster (Half Elf)
----Wizard-Shock (Sylvan Elf)
So each character is Level 4 and everyone took Potent Cantrip. The results are all over the place.
1) Shadow Dagger (never worked for my Rogue or Wizard)
2) Fire Bolt (worked a couple times for my Wizard and properly showed the reduced damage, but then it "missed" for multiple rounds. It NEVER worked for my Paladin, who chose Fire Bolt as a High Elven Cantrip)
3) Sacred Flame (NEVER worked for my Cleric)
4) Acid Splash (NEVER worked for my Wizard)
In summary, I "only" saw Potent Cantrip work for the Wizard, but then it would fail a round later (full miss, no damage). This feat is clearly not working for the Rogue, Cleric, and Paladin (High Elf).
Thanks again for a great game! I hope you untangle this mess soon and Iron Legion (that's broken as well).