This add-on is so useful as I work with google sheets, and I've recently moved from chrome to firefox and now I just can't get it to work at all :(, I don't know if it's my computer or the add-on but I would really like it to work on firefox.
I tried the shortcuts and they work, they do change the add-on configuration, but it still does not highlight anything.

OH YEAH this add-on helps me work with spreadsheets on large monitors.

And only 4 stars because sometime it does not work. I had to restart Firefox for it to start working on a blank Google Sheet. And I cannot make it work on an existing sheet. The color-pop-up options always work, however there are no highlights on my Shared sheet, in my Google Enterprise Work account. I might open a bug report with the author, to fix my bug, because I like this Add-On!

EDIT: Developer found and improved my issue, thank you!