InTune API 500 Internal Error

Question

I'm trying to update an app in Microsoft InTune with a new version. I can create a new version with this endpoint: https://graph.microsoft.com/beta/deviceAppManagement/mobileApps/{appId}/microsoft.graph.windowsUniversalAppX/contentVersions/

Then I try to create a new file with this endpoint:

https://graph.microsoft.com/beta/deviceAppManagement/mobileApps/{appId}/microsoft.graph.windowsUniversalAppX/contentVersions/{fileVersion}/files

but this endpoint gives me a 500 Internal Server error. Has anyone experienced this before? Is there another route to complete what I'm trying to do?

Thanks,

Doug