Hi Aaron Wade,
Thank you for posting your query on Microsoft Q&A!
Normally we see this issue if a user is not logged into Edge with the same Entra ID user account they are trying to access the application with. Or if a user is using an incognito browser window.
One other possible problem can be if the user does not have a PRT for some reason. We have details here on how a user obtains a PRT on an Entra ID joined device - https://learn.microsoft.com/en-us/entra/identity/devices/concept-primary-refresh-token#how-is-a-prt-issued
We have some guidance here on troubleshooting PRT issues - https://learn.microsoft.com/en-us/entra/identity/devices/troubleshoot-primary-refresh-token#step-1-get-the-status-of-the-primary-refresh-token
Do let me know if any of this helps, or if you have further issues I would be happy to help.
Kind Regards, Donal