> if you had very old installation of OWB and fullscreen fix script, the allowed
> sites list for fullscreen fix script might have been outdated. I noticed once
> that newer scripts added more urls to that list than older ones.

Yes, I remember I had this problem as well:

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=3&topic_id=9462&start=119

> in that case you should have removed the script completely and not just updating
> its file, before adding it again as newer one.

Strangely, the screenshot in comment #10 shows an "allowed sites" list that is the same as that of the current version of the script.