Not every setting is being synced. Check browser.tabs.loadBookmarksInTabs, it should be true.

Finally! Problem solved. Thank you. Why was this feature stuck in "false"? I have settings as one of the items for syncing. The laptop in question which was misbehaving has the same settings/check boxes as my other two and it was just not happening. What could be the cause of this? Clearly a glitch, but an annoying one since I have tried everything on my end (shut down, restart, clear cookies, cache...) without a correction. Your solution is over my head so it is not one I would have done. Just curious, what and where is the setting to have tabs opening individually when I click on a bookmark ?