Gustaf,
I have no idea what possible be causing this strange behavior in my installation.
I've upgraded to NaviServer/4.99.19 (tar-4.99.19) and acs-kernel-5.10.0d30. last week. Plus it's a fresh install. So it's too recent to get myself "forking around" anything in the core 😊
It could be NGINX cache. However, it happened only in this instance, among others, which are served by the same proxy.
Anyway, all it means is that I need more time to dig further into this problem and find the actual cause of it.
Best wishes,
I