This may be the same issue. Same material with bumb channel on and off images attached. I used that material a lot with my previous projects.
Same with the RC5. Also, the faulty areas changing according to camera view. Seems like this happens with cubic mapping.I have builded a basic test scene with the Cosmos materials. It's the same.https://we.tl/t-yaBaLEjx4h
I THINK It’s fixed in the new “official” release - from my very quick test