Interesting one this. If I check a toolbar in explorer it disappears and vice versa.
In the attached screenshot the toolbar for networx is checked and does not show. The toolbar for classic shell is not checked but shows. This seems to have just started this morning after applying the Patch Tuesday updates last night.
I can live with this but does anyone else have this problem?.
I cured the problem by uninstalling and reinstalling Networx. No idea why it happened though.