After you file

The IRS sent the first direct deposits on Monday, April 13th to everyone that filed 2018 and 2019 tax returns with direct deposit information included.
Two days later, on Wednesday, April 15th, the IRS opened the Get My Payment portal to allow those same taxpayers the opportunity to update their direct deposit information. OOPS! They should not have let any of those who had stimulus funds already sent to them update their information.
In the meantime, an unknown number of stimulus payments were rejected for various reasons and returned to the IRS.
Some of these rejected returns belonged to some of the taxpayers who had managed to update their direct deposit information even though their initial direct deposit had already been sent out. Updating bank information AFTER a payment has already been scheduled should not have been possible.
THIS is the "glitch" in the Get My Payment portal that you are hearing about so much. Those who happened to be able to update direct deposit information SHOULD NOT have been able to do so.
So just because you did update the information, the timing of the start of the stimulus payments being sent before the opening of the Get My Payment portal means that your update was invalid IF you were included in the initial wave of stimulus payments.
The reason why is because the first wave of stimulus payments never had an initial delivery date scheduled in the portal because the portal did not exist when they were sent. The initial status that users saw when logging in to the portal for the first time never showed that their payment had already been sent, so you were able to update direct deposit information when you shouldn't have been able to.
Only after being rejected and sent back to the IRS, which was also AFTER the Get My Payment portal opened, were those stimulus payments processed through the Get My Payment portal as rejected stimulus funds (for whatever reason) and then repopulated to be included for delivery by check to the address on file with the IRS. This is when the Get My Payment portal updated your status to show your delivery date of a paper check by mail. This is inline with the IRS posted policy that all stimulus payments returned to the IRS will be processed by mail. They do this as a security measure to prevent funds from trying to go into an account or to a bank that had already rejected the money once.
The same thing will happen going forward in the next waves of deposits to anyone who has their stimulus payment returned to the IRS. The IRS will continue to process returned stimulus payments by mail if they are rejected by the banks or the account is closed, etc.
If you initially had a direct deposit date, and now you have a delivery date for a scheduled check then, unless the IRS announces that they are changing their policy of not resubmitting rejected stimulus payments for direct deposit again, you should fully expect to receive a paper check that will be mailed to the address that the IRS has on file for you, on the scheduled day you see in the Get My Payment portal.