Comment 10 for bug 1840597

Thank you for checking that!

This is always frustrating with distro builds, they may disable features for any number of reasons, which can cause things like this.

One more step, if you have time. Can you install this sample extension on the Canonical build and see if it works or not?

https://github.com/mdn/webextensions-examples/tree/master/menu-search

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Temporary_Installation_in_Firefox