[ffhhj]

After installing the extension icon doesn't show up, not even in the Customize Firefox tab, and the extension is active. There is no menu whatsoever.

[Temporal_Trout]

Odd, for what it's worth I'm running `Mozilla Firefox 97.0.1` and it shows up.

The docs are here:https://support.mozilla.org/en-US/kb/containers#firefox

The only thing that stands out to me is "Containers are disabled in Private Browsing windows and when Never Remember History is selected in your privacy settings."