Hi JohnnyHart, This is where Zorin have tweaked Gnome - to get the Windows 7 look they disable that top Panel which is an inherent ‘traditional’ Gnome DE. I always leave off the following from Gnome Tweaks:
System, Places, Top Panel. I seem to remember that activating one or other of System/Places can sometimes lead to the top bar appearing. It could well be that there has been a ‘Gnome’ update through the backdoor that screwed the Zorin desktop up. 
I can’t double check that for now as I am in FerenOS.