Mozilla isn't the one to correct this problem. HP needs to do it. It's their add-on, their responsibility to keep up to date with every new Firefox release.

I also am having this issue since the latest upgrade. :(

I worked with the HP reps the other day to get help with this solution; took two of them to get it accomplished, but they finally got SimplePass working with IE11. When I asked specifically about the Firefox add-on the reply I got was, "Firefox is updated too often for HP to keep up, we simply can't do it."

Sounds like they have given up to me.