Scenario: User has read access to a library, but for one file has been granted edit access. They can edit the file through web just fine. When they utilize Sync, the library is synchronized properly using OneDrive. File explorer view shows locks next to all files except the one. However attempts to make changes to that that offline copy fail with message: "AUTOSAVE FAILED We have not been able to save your changes. Please save to a different file in order to keep all your changes". Attempts to Save As directly to the library fail.
If you stop sync, then the user is able to open the file directly from their desktop program and edit. But with the Sync copy in place it creates this problem.
It seems that:
1. While the synchronized library files seem to be aware of permissions, OneDrive isn't configured to properly handle that and gets stopped at the fact that the user does not have edit access for the entire library.
2. This problem somehow causes issues even with attempts to open the file with a desktop application, even if they are opening it directly from the SharePoint online source. This part has been intermittent. Sometimes I get a change to save, but with errors that try to indicate it's not working even when it does.
When I remove the sync, the problems go away. We do maintain version history. Possibly that is playing a role, but the user with edit access should (and can) create new versions.
Just wanted to feel out whether this was known behavior and if I'm missing something.
Generally I am steering away from use of Sync. There are however some use cases that are ideally suited for it.