I uploaded version 5.5. Can you download it and just run that extension file. It should ask you to upgrade from 5.4 to 5.5 and request permissions again. Let me know if that works!
Thanks for the quick attempted fix! Gave it try and it asked me to upgrade from 5.4 to 5.5 as expected, but still didn't request permissions. I still get the error when I try to export using it.
Wish I knew where it stored the permissions, I imagine there's just one line in a file somewhere that needs to be erased or something.
Update: I figured it out! It seems to be some sort of conflict with another export extension I sometimes use GMLink
https://pr0te.itch.io/gm-link
Disabling GMLink and restarting Aseprite fixed it, still no permissions pop up, but I guess the old permission I set ages ago maybe worked once GMLink wasn't running?
Turning GMLink back on causes the error to re-appear so looks like that's definitely the culprit.