If you scroll through the group or any other tax group out there you'll find this is a common theme...IRS is behind in payment processing, even electronic payments.   

You can have your client call the EFT phone number on the 8879 and verify that its scheduled, but dont be surprised if it take a couple of weeks to pull.

https://proconnect.intuit.com/community/proseries-tax-discussions/discussion/re-electronic-withdrawa...

It is possible you were affected by an issue with ProSeries that caused 2021 Q1 Estimated payments not to be withdrawn. Please see this post for details and instructions on checking to see if your client was impacted. 

https://proconnect.intuit.com/community/proseries-tax-news-updates/discussion/1040-es-payments-not-b...