I think it is no conspiracy that scopely stealth fix raids with the upcoming gambit raids lol. The team requirements are shitty lolol and probably wants everyone to buy exclusive gambit raid health packs at 99.99USD at 99% discount!!
Definitely very random. I did two greek raids today with mod, one was okay, the other had combat invalid. Campaign too, very strange. No chance to try it in DD
What were you doing when you encounter this? What values were you using and which game modes? It seems to be happening in most game modes but rather inconsistently