Edge Chromium protected media not working

[disturbedone]

Opening Edge Chromium (80.0.362.62) to

https://open.spotify.com

allows media to be played. But after waiting ~5min it will stop working and display:

Enable secure playback in your browser

The Spotify support site says:

you simply need to enable the Widevine plugin or download a media pack.

The Media Feature Pack is required when using the 'N' version (Europe only) of Win10 but we're not using that. And the Widevine DRM plugin is set to 'Default' in edge://flags/#edge-widevine-drm and changing it to 'Enabled' makes no difference.

Deleting the user's local profile will get it working again but after ~5min it will stop again with the same message.

This all sounds like a Group Policy is applying after a period and stopping it but there's no Group Policy setting that I can find that would do such a thing. We're only in the testing phase of Edge Chromium and there are only 6 settings (search provider, start page etc) in a GPO and all others are 'Not Configured'.

[UPDATE] I've found that C:\Users\{username}\AppData\Local\Microsoft\Edge\User Data\WidevineCdm\ exists but as soon as subfolder \WidevineCdm\4.10.16.10.0\ is created the error appears in Edge. This folder appears after a few minutes when Edge is open.

Anyone know why this would be happening?

This occurs on both Win10 1703.1 (15063.2108) and Win10 1909 (18363.900).

 

[disturbedone]

It appears that this was an issue with Edge Chromium v80.0.362.62. Upgrading to the current v85.0.564.51 allows it to work and it does not create the \WidevineCdm\4.10.16.10.0\ subfolder.