FIXED – SharePoint Online missing Sync button

While troubleshooting OneDrive I noticed an end user missing the “Sync” toolbar button.  The fix was to update Document Library settings to display “Sync” so that we could connect and take the Document Library offline.   After clicking “Sync” we were able to connect to the OneDrive desktop client and download all files.

Cheers!

Steps

• Document Library (Classic View) -> List Settings > Advanced settings > Offline Client Availability >
• Allow items from this document library to be downloaded to offline clients?  YES

Screenshot