Firefox extensions keep disappearing
I have several Firefox extensions (uBlock Origin, HTTPS Everywhere,
NoScript, Privacy Badger) installed from Debian packages. Recently (the
past few weeks / months?), they have begun to disappear from Firefox -
they stop funcioning, and they don't appear on the toolbar, nor are
they available to add to the toolbar from the customization screen,
although they are still shown as installed and enabled in about:addons.
Doing "Refresh Firefox" from about:support brings them back, and they
remain present for a while, but then they inevitable disappear again. I
tried deleting and recreating my Firefox profiles - this did not solve
the problem. I have the problem on two separate Debian Unstable
installations. I tried searching the web, but all I can find are old
articles that don't seem to address my particular problem. Anyone
having similar problems? Any ideas, solutions, or workarounds?