I've browsed many of the other related threads but don't seem to see any solutions that apply.
Anytime I open Firefox (version 51.0.1) and the 1PW extension to login to a given site I get a tab that opens stating the extension has failed to open. At the same time the main 1PW app opens prompting me to login. Once logged in I then get the small site specific cue. Previously with Chrome this was not an issue.
I have uninstalled/reinstalled the extension and also turned on beta but no luck.
I've exported the logs per other thread instructions and can send when needed.
1Password Version: 6.3.359
Extension Version: 4.6.3.b3
OS Version: Windows 10
Sync Type: 1PW