Thanks for telling this. I will fix this bug.

Edit. I uploaded new version, now it should work on local files.

Edit 2. Thank you for the feedback. I will try to fix those key shortcut issues and see if the UI changes you proposed seem like good ideas. I noticed too now that Multi Account Container's shortcut is ctrl + . I guess it changed recently. It would be best to change the default shortcut.

Edit 3. About ctrl + ] not working, I was able to use both. Maybe it's some keyboard layout issue. I need to press AltGr to get [ and ]. I will make an issue on GitHub. Would you like to come there to discuss about these? https://github.com/fluks/mark-location-webextension/issues/31