Web Shield blocking Firefox add-on

Web Shield is blocking an add-on I’m using in Firefox: disconnect.me.
I’ve attached a screenshot of the Avast alert.
I can’t find a way to allow the extension to run. I don’t want to turn off web shield either.
How do I allow this extension to run?
Thanks!

Web Shield is blocking an add-on I'm using in Firefox: disconnect.me.
No it is not. It is blocking the URL it is connecting to

https://www.virustotal.com/gui/url/3749e467b768fcdfae422c459a4e3863a88a2870b003a4032e4878eaca6dde96/detection

Snap - I also sent off a possible URL FP to Avast yesterday.

I have been using this add-on in firefox for longer than I can remember.
I felt comfortable enough to use the Create Exception - my Alert Window differs slightly from the OP, see attached screenshot.