Mac OS 10.13.6
Sense App 17.3
Installed Sense app on Mac.
Install and operation OK.
Installed browser extensions on Chrome and Safari and all OK and functioning.
Installed Firefox browser extension. Firefox notification box says it's now installed. Firefox Add-Ons shows it is installed. But Sense App continues to tell me that it is NOT installed and prompts me to install. I removed it and re-installed.....same notice from Sense App, along with the yellow exclamation mark on the App icon telling me it isn't installed. Shut down Firefox, and green checkmark returns to Sense App.
Are Firefox preferences on default or did you change anything?
You could try to reset Firefox completely, leave setting on deafult and then reinstall the extension. Restart MacOS once.
If the issue still persists, I would recommend to get in touch with our support team here via chat or phone so they can investigate it further.