The IRS may not be able to debit your payment until after the deadline, due to high e-filing volume. In addition, it can take your bank another few days to post the debit to your account.
https://ttlc.intuit.com/replies/3299924
Make sure you entered the correct debit info :
How do I review the method I chose to pay my federal income tax with, after filing with TurboTax Online?
You can verify the tax payment method you chose on the Electronic Filing Instructions for your 2018 Federal Tax Return page, next to Balance Due/Refund. To see the page, follow these instructions:
1. Open your return if it’s not already open.
2. On the [Your name], your 2018 federal return was accepted! screen, scroll down and select Add a State (don’t worry, we’re not adding a state) to access your tax forms and worksheets.
3. On the left side select Tax Tools then Print Center.
4. On the TurboTax Print Center screen, select Print, save or preview this year’s return.
5. On the next TurboTax Print Center screen, select 2018 federal returns and Include government and TurboTax worksheets (optional) then select View or print forms.
6. The information will be on the first page, Electronic Filing Instructions for your 2018 Federal Tax Return next to Balance Due/Refund.