I’ve only had this happen one time with a MG MO: one of the three MOs I deposited for $499 was rejected by my CU (I was using a Co-Op ATM for deposit). The deposit went through initially, but then I noticed $499 and a $12 “deposit cancellation fee” on my checking statement. I called my CU ASAP, and provided them with the receipt that showed the MO had been accepted for deposit. They ended up mailing the MO to me and crediting the fee; I just deposited it in my bank account and the ACH’d it back to my CU account. The process took about two weeks for me to get the money order back once after the deposit failure.