Just checked your screenshots, what is weird is that you received a 500k withdrawal the same day 5h earlier but that the other one is still processing.
The other $500k withdrawal request, if I am judging correctly, was about 4 times within 2 days, which is 2 million dollars withdrawn from an account. This might either be because the other withdrawal was not a success, which they later reversed to the account, or the other few were successful before the other recent withdrawal. If they are successful, it's also enough reason for a new withdrawal delay.
This is an online casino we are talking about here, and only a few online casinos can pay this huge amount of money to their customers within 48 hours. I am not saying the withdrawal was purposefully suspended, but we could also look at it from that angle too. And the technical team will be working all hands on deck to see if there is any suspicious gaming behavior. They will always come up with a solution, I believe. The OP just has to give them time. Judging by the amount, I know it warrants panic, but panic can't resolve anything here either. Let's just wait for the Dullbit representative to come and explain to the OP.