After the recent update (May 2020), and reinstalling FF, I added this extension after having used it before. This time, however, it completely blocked me from accessing Amazon and Amazon Smile. It was by chance that I found through Bugzilla that this is a recent problem with the latest FF update. Once it was disabled, I had no problems accessing Amazon Smile. May I suggest that a note be posted on this page acknowledging that there's a problem. I thought it was a FF problem, and maybe it is, but just trying to prevent any anger from being misdirected.