UPDATE: we figured it out, private windows break the extension. a disclaimer has been added to the description to reflect this.

ORIGINAL REPLY:
hey, i just submitted 4.0.2 which might fix the issue you're having? not quite sure but give it a shot and let me know how it goes!
also since your issue wasn't appearing (no clue why.. unverified email? github shadowban??) i submitted it myself to keep track: https://github.com/noblereign/GX-Mods-Extension/issues/9
if it doesn't fix it then yeah send me a friend request on discord @noblefurlyfe i'll try my best to figure it out