If anyone can offer any advice, I need some help trying to retrieve missing data from a SharePoint 2013 MySite/OneDrive for Business Site (On-Premise)

Backstory: We have users that have SharePoint 2013 Enterprise set-up with OneDrive and they use this religiously for sharing OneNote notebooks which are then locally synchronized with the OneNote 2016 desktop application. I received a call from a user that they were no longer able to synchronize their OneNote notebooks. After having a user log into OneDrive via SharePoint, I noticed that no files were contained in their OneDrive sites as if they were all deleted. This is for all users (roughly 40) and none of them have their notebooks anymore.

Notes:

• Windows Updates are disabled on this server and no known infrastructure changes were made that would change availability, permissions, etc.
• If I go into SQL Server Management Studio 2017 and navigate to that particular instance/database, the database is still 4.2GB. I attempted to restore this with Veeam prior to the date it happened (May 23rd) and OneDrive displayed a blank page, so I restored it to last night's backup (June 4th). IIS was restarted.
• There is nothing in the Recycle Bin for the end user or the Site Collection Administrator.
• I've dismounted and reattached the database with SharePoint Management Shell. This made no changes. IIS was restarted.

I've reviewed this article and when I query a user's library with the requested answer (and my relevant information/values), no data is returned. If anyone has any insight, I would greatly appreciate it.