This add on may have had issues but there are two things to consider. (1) It is one of the most useful add ons available for any professional or research oriented person. (2) I determined that the problem was not the add on but firefox itself. In light of the MANY updates to firefox, the issues seemed to go away. I figured this out when I use the add on in Chrome and it worked perfectly. This was followed by many months of avoiding firefox. I'm happy to report that firefox is back, and so is this add on. Software is a technology that REQURES a consistent human language and problems occur when teams mix and match. It's been known for a long time. The best teams speak all English or all Spanish or all (ANYTHING). I think firefox got caught up in this reality.