As of now this is a known issue in the latest version of Lightroom.
I would request you to please use the workaround : https://helpx.adobe.com/lightroom/kb/synchronize-folder-failure.html
I understand, however this is a known issue with the current version of Lightroom, that Synchronize Folder is not working.
So we are requesting the users for the workaround I mentioned,
You are Welcome, Glad to help.