Picked up an Anima Power in Torghast and the effect was “Placeholder”, rank Common, no image, and the button said “Placeholder”. See link: Bug
Clicking the button gave me no anima power and the window went away.
When you run in to something like this, it’s best to use the in-game bug report tool so the QA department can see exactly where and what the issue might be.
There is no more in-game bug report that I could find. Used to be a button in the Support menu, but that appears to have been redone and things have changed/moved around.
Since I can’t edit the OP (I am OP), this happened 3 times on Floor 5 of Coldheart Interstitia.
https://us.forums.blizzard.com/en/wow/t/no-report-bugs-or-suggesions/724265/11
That should show you where to find the in-game bug report tool.