Thanks for requesting some updates about this issue, @RobHere,

Joining the thread to share some updates about the "There was an error communicating with the QuickBooks Payments Service. Please try again later." error in QuickBooks for Mac. 

There has been some reported issues about this which was escalated to our engineers for a fix. However, the investigation was tagged closed as of today (05/05/2021). This means that those users experiencing the problem has already been taken care of, and can use the service again.

However, we do not assume that everyone else had their services up and running, which is why we still recommend contacting our Payments Team again. This way we can re-open the investigation, so our engineers can release additional workarounds and fixes specifically for your account.

I will share the suggested workarounds posted by our engineers, then try to check if it works for you. First, you can run the Verify/Rebuild Utility to fix minor program issues in QuickBooks Mac.

The next workaround is to configure and verify your firewall settings. You'll see the steps through this link: Verify application firewall.

Lastly, delete e-invoice keychains, then reboot QuickBooks for Mac and try again. To delete the keychain entry:

1. Quit QuickBooks so that it isn’t running.
2. Use Spotlight in the Finder to locate KeyChain Access – an Apple utility that ships with macOS.
3. Launch Keychain Access.
4. In the Window that appears select All Items from the Category section on the left.
5. In the search field at the top right type QuickBooks_eInvoicing
6. You should see a keychain entry that looks something like this: QuickBooks_eInvoicing_577604244511786429_F51354FE-674B-440A-8C99-4E21CED2A8D7
7. Select that entry and delete it (File->Delete menu).
8. Launch QuickBooks and create a testing invoice that uses e-Invoice.
9. You’ll be prompted to log in to payments again since the keychain entry is gone.

We want you to try these workarounds to test if this is a software or connection issue. That way, it's easier to rule out the problem when it gets reported again to our developers.

Kindly post an update here, as I want to make sure this is taken care of. I'll be right here if you need further help.