I don't want to accuse anyone, but this seems like a strange gambling pattern. And all small bets and the last 600. I think 1xbit also thinks this is a separate betting pattern. Even at the highest level, strange things happen in the world. I don't know why 1xbit canceled the bets, but it could be that the terms and conditions have been violated.
You still don't know why 1xbit canceled the bets, that's strange. Don't expect 1xbit to to be transparent and announce everything, they will try to do whatever they can to scam people, so better to bet on other reputed sites and not on 1xbit.
I think 1xbit reserves the right not to announce that either, because cheaters then know how to use a new exploit on that.
1xbit are cheaters themselves and how can a cheater (player) beat another cheater (house)

People still do not want to listen and try their luck with 1xbit; it's their fault only.