Tested with transmission 2.84. Might be something to do with my odd setup (transmission is in another subnet, behind SSL and password) Other addons such as "Add to Transmission" and "Transmission easy client" work without issues
Thanks for leaving a one star review instead of contacting me privately :) Subnets and SSL should be fine — I use it with not just SSL but a client certificate — but I haven't tried setting a password. I'll try that soon.
UPDATE: tried setting a password / required authentication. It works! Firefox just asks for the password with the standard basic auth dialog.
