Question:

Is there a way to retrieve all the documents that are checked out to Office Online?

Answer:

As of the V21R1.2 release, users cannot check out documents to Office Online™. 

At the end of 2021, Vault no longer supports editing with Microsoft Office Online™. Users must check in all documents previously checked out to Office Online™ before the V21R3 release in December 2021 or lose those changes. 

Admins can extract the information from the Document Audit History. Here are the detailed steps.

1. Navigate to Admin --> Logs --> Document Audit History.
2. Filter on the proper timestamp.
3. Add filter Event in Online Check Out and Online Check in.
4. Click the Apply button.
   
   
   
   
5. For documents that are only checked out to Office Online but not checked in from Office Online, The documents need to be checked in before the V21R3 release.

Related Documentation:

Vault Documentation: Vault Help