Joe, for me, there is an 'Extensions" icon (a little puzzle piece) in the toolbar. After I unpinned the WBE options popup (the latter is the only extension I have installed in Firefox), when I click on the puzzle piece I see the WBE listed in a drop-down and there is a gear icon next to it. When I click that gear icon, it gives me the option to pin the WBE (actually the WBE options) to the toolbar. It took me a bit to figure this out, but even without the WBE options being pinned, you can still set the WBE options in this way: In the top menu, click on Firefox, then Preferences. On the left, down at the bottom there is Extensions & Themes. Click on it and you will see a list of the extensions you have installed, as well as suggested extensions below them. You should see the WBE listed in the top part and presumably you will see that it is enabled (is it? - there is a little toggle next to it for this). Next to the toggle are 3 horizontal dots. Click on them and you see a dropdown with Preferences as on of the options. If you click that, you get the WBE options that you can configure.
If the pinning I described above still does not work, can you go to the WBE Preferences as I have described and tell me if you then still see a blank page rather than options you can set. If you see options, set a couple to your liking and then tell us if the WBE work as advertised on a WikiTree page. I hope you have success.
If you are on Discord or any other interactive communication system, contact me (or tell me which one) and we can try and figure out what the issue is on you machine.