I haven't been able to sync one of my trees for the past 2 days. I've closed and re-launched FTM, as the error suggested, but I continue to get the message "The last sync failed. An error occurred while 'Analyzing changes from Family Tree Maker'. You may want to restart FTM and try again later."
My two other trees sync fine, but this one does not -- this is the only one that I have actually done work on in FTM. Since that time, the file won't sync. I only did 2 merges from online searches (hints from Ancestry.com), other than that, the data should be identical since I did a fresh link-and-sync before that.