I have Sync Issues

The standard sync error message looks like this:

Open

In theory, these errors are not related to the work of the Add-In.

The synchronization issues folders contain logs and items that Microsoft Outlook has been unable to synchronize with your email servers.
Having messages in these folders is a normal function of Outlook as they are error checking mechanisms that the program uses to sync your email to email services.
About the details of what is contained in the Sync Issues folder and how it works you could read here.