Too much to speculate on here. Casinos routinely have collection issues, they attempt to work with big spenders, to keep them coming back. The casino would wait until either they believed they weren’t going to get paid without a court order or there is a limitation period which would expire. In Ontario you have to start a court action within 2 years or lose the right to sue.
To get a draft, you must have the funds in an account. The issuing bank removes the funds from the account at the same time the draft is issued. Banks can refuse to honour drafts for a number of reasons, such as alterations, the payor advising of an irregularity (account holder did not authorize the draft), a cheque or transfer into the account the money is from is dishonoured after the bank issues the draft, etc. In some jurisdictions legislation prevents banks from making payments if the payment is for something that is contrary to that countries laws, ie. gambling, or paying for a criminal act. All just speculation in this case.