When I open any web map I own in Map Viewer using Firefox, there is no left-hand toolbar (it's not just collapsed, it's completely gone).
When I open a blank map in Firefox, I see the toolbar. However, after using it to open a map, the toolbar disappears completely.
However, the toolbar is there and behaving normally in Chrome for the same web map.
This Firefox behavior just started this morning. Is there a solution to this?