"Force Sync" not working

My bookmarks do not seem to be syncing between my computers. I have updated versions of Firefox on both computers, sync is turned on, the same account is logged in, and the bookmarks option is selected on both computers. But when I force sync, there is a bookmark missing on one of the tabs. The most recent bookmark I've added. This has happened in the past and I had to manually add the bookmark.

Any suggestions?