My clients are experiencing the same issue, today is the 20th and no withdrawals yet.  Sounds like a delay rather than a problem. 

One of the returns was filed on April 16, it was accepted. Does anyone know if the IRS will skip the 1st quarter because the return was filed after the April 15 withdrawal date?    Last year, a return was rejected when filed after the due date of the extension payment.  Since it was accepted, I am planning that the payment will be processed, but would love a way to find out for sure as we can send a payment if the autopay will not work.