Hello Cryonic, I'm sorry to hear that this add-on isn't functioning
properly on your tables. To troubleshoot, could you please confirm
if it doesn't work on any table in general or specifically on
certain ones? Since, I personally use this add-on without issues, an
outdated Firefox version might be a possible cause?. It's also worth
mentioning that some websites with complex table structures may not
support this add-on. If you can provide me with the URL of the
website where it isn't working, I could investigate further to help
resolve this issue. Thanks.

Hey zyzzza, I just updated the version from 1.18.0 to 1.18.1 (to have parity with the chrome version) there was a bug on 1.18.0 that caused some websites tables to not sort. I'm not sure if this was the issue you encountered, or not. Let me know if updating the extension works. If not send me the URL of the website you are trying to use the extension on and I can take a look at it. Cheers.