You aren't using Private Browsing mode?

• https://support.mozilla.org/en-US/kb/extensions-private-browsing

Did you click the Extensions (puzzle piece) button to see if you can pin its icon to the toolbar?

• https://support.mozilla.org/en-US/kb/extensions-button

I don't use Private Browsing. I'm sure this is operator error, however... rt/clk next to Firefox icon and get customize. I know this screen, but no where is OneTab visible. Rt/clk OneTab icon on menu bar and it's checked (see #1) Chkd Options (see #2)

Can someone pick up from my response and suggest a fix? Thanks.