Excellent addon.

But something broken since Firefox 66, and something is conflicting with Zoom Page WE. Not necessarily this addon has problem.

So far, I was suspecting uBlock Origin as faulty. My experience was, when starting up Firefox, no page is loading, until I disabled uBlock Origin addon. After disabling uBlock origin, every pages loaded . Once this happened, I was able to enable uBlock Origin again , until exiting Firefox again.

Recently I've noticed Zoom Page WE didn't work either. When I disabled Zoom Page WE (instead of uBlock Origin) pages started fine after Firefox start too.

Now noticed following. I actually use about:config 'browser.tabs.remote.autostart' on FALSE (multi-threading related). If I change to TRUE (to default), then pages starting to load correctly again with both Zoom Page WE and uBlock Original enabled.

Conclusion for me:
With Firefox 66, browser.tabs.remote.autostart cannot be FALSE if both Zoom Page WE and uBlock Origin enabled, because after Firefox start no pages are loading. It only works if one of the addon disabled or if browser.tabs.remote.autostart is TRUE. This is some bug that should be corrected somewhere.