If device enrolls, APNS should be OK. Even if expired, devices will enroll. I can attest since I had an old assignment that worked for a long time after expired.
Managed distribution sToken expired?
Do you have enough licenses for the distribution in your OG? Not likely as you wouldn't be able to over assign licenses, but still check. Maybe app license transfer from Location A to Location B in ABM could lead to over assignment.
Next, with the recent changes to VPP / App deployment, check your VPP sToken. Have you in the last year or so, downloaded a new copy of it (sToken) for your assigned location and uploaded that to your WS1?
WARNING: If you have not, I suggest you call Apple Enterprise Support to receive guidance on how to properly do it. Earlier this year I spent one hour with Enterprise Support who guided me. I didn't want to negatively impact my clinical devices.
Hope this helps.
