I had a similar issue ages ago with adblockerplus but i did a fix and it reconfigured itself. But with ublock origin im not sure how to do that as its supposedly turned off.
I think i'm going to be moving away from firefox. It annoys me how it doesnt fully integrate addons like it used to. I've noticed a few times an addon will change the browser but when you install something else or uninstall an addon it doesnt reset the values back.
I can't remember what I did last time when I got the adblockplus browser to check my settings and then it worked again.
-- update again..
I don't think its removing ublock origin when i clicked remove. I removed it.. closed the browser, re-opened the browser and it appeared to be gone. Later on I thought i may as well re-add it again. I did so and all the settings were still there. it had still remembered I set it to be unblocked on the roadworks site.