Endnote x8 Sync Error: "You have made changes that have not been synced"


Another problem with Endnote x8. I have a user with Office 2016 and Endnote x8 having issues closing the EndNote library. Every time she tries to close it the following message appears: “You have made changes that have not been synced. Do you want to sync them now? If you do not sync the changes now, they will be sent the next time you open this library”. After clicking “yes”, the library appears to sync for about 3 seconds then the same message appears over and over. The only way to exit the program is to click “no”. Any thoughts on how to resolve this? thanks!

turn off auto syncing in the preferences (see attached image)  That is what I do.  Then I sync when I want, by clicking the sync button, and go to lunch.