Sorry, but this unfortunately is a tactic I have run into at more than one Rival casino. It is NOT a technical error as you stated. I can attest to this from chasing down former rival managers in the past who clued me in , after I could not fiquire out why it was happening. I would make some nice withdrawals and then this started happening at those casinos. Its a tactic used mainly against depositing players who have had some good luck, a way around of bonus banning them out right, they simply lower all the bet sizes, without letting you know until you start to play.
Note, i don’t play at Superior, so I can not attest about them specifically, but in general I can comment.