I have used WiseStamp in the past so am quite familiar to it. Only I have been using it intermittently. I remember that it used to work excellently on all of my email accounts be it Yahoo or Google but now I have installed it again on all of my browsers and although it seem to work fine in Gmail it has a problem with Yahoo - the WiseStamp signature doesn't appear at all and I can't insert it either.
I must say that, when I sign into my WiseStamp account and I edit my signature, I do can see it, but only in my "preview signature". Otherwise, I can only see it in my Gmail.
In order to solve this situation, I have followed the advice from the official site but, unfortunately, that did not helped much. Practically, they ask me to reinstall the add-on. I did that three times, but with no result. I did a Google search over it but it seem that I have no luck in it. All I could find was an article apparently suggesting that the new changes of Yahoo mail can affect some codes, or something like that. It occurred to me that this might be the cause of the unusual behaviour of the add-on.
Even so, this must have a solution, and if you know how to fix this and make the WiseStamp signature reappear in Yahoo mail, please, tell me!