I just found out that I have been dealing with this problem recently. My Lightroom desktop has been showing that I am syncing 2,226 photos since the start of the year 2020 yet I don't have any error messages in my Sync Activity (Preferences>Lightroom Sync).
Recently, I have discovered that I have this error message when I accessed Adobe Lightroom using the web/browser. I have attached the screenshot and it seems that I cannot delete or remove it. Any idea how to address this problem?