"Starting up..." at the bottom of sidebar and nothing but white above that.

I see that there was an update earlier today so I'm sure this is related to the update. A brief overview of my setup: Running Windows 7 64-bit on a Dell Optiplex (business class) desktop. Using Firefox 57. Firefox has KeeFox (KeePass extension), Tamper Monkey, an IP reporting extension, and Disable Tab Detach extensions.

When I logged on to my computer today (about an hour after the update was published), Firefox started up as it is supposed to and the Tree Tabs looked fine. I was even switching between tabs for a minute and then it disappeared and left a white empty canvas in its place. No menus, no groups, nothing except a very very small loading wheel and "Starting up..." at the bottom of the side panel.

I tried the Reset at the bottom of the plugin options page, no change. I also disabled and re-enabled, restarted FF and even completely removed the plugin from Firefox. When I re-added the plugin, I got the same "Starting up" deal. I clicked the plugin icon to open/close the panel. The panel closed, I clicked again to open it but nothing happened. Furthermore, the options are now no longer accessible.

I am at work so can't produce a screenshot now. Will post screenshot on lunch in about 2 hours.

Thank you!