Called to verify funds on a cashier's check and paying bank indicates check "might not clear"??

This is sufficient info to place an reasonable cause hold?

What do they mean "might not clear"? The only scenario that I can think of that would cause a cashier's check to not clear is if the FDIC came in and closed the bank at 5 o-clock tonight. Otherwise cashier's checks are guaranteed funds.

Now, if they said they never issued a check with that check number for that amount or the payee you provided is not the payee of record, then you should be sending the person down the road.