I get message “An error occurred: You are not permitted to view the requested resource.” This does not seem like confirmation. And I was not asking to see anything. And I am logged in as a core developer.
If the post was the recent one that I just saw, it might be that the author deleted it just before you tried to flag it.
Moderators already received multiple flags and handled them. Once a post is deleted it cannot be flagged, but the page won’t show that until it’s refreshed.
And FWIW, the same thing sometimes would happen to me as a mod when I click a response to flagged posts in the moderation review queue, that are been dealt with by another mod at the same time.
Thanks. Got it.