I usually use tidy plates threat plates and it changes the colour on mobs depending on threat yet on todays raid its not doing it. I changed to KuiNameplates thinking it would fix, but it has the exact same issue.
this started happening on wednesday/today I cant remember correctly.
No clue what your problem is but i've been having this problem where nameplates get stuck after the player/mob i just killed and just stays there inthe middle of my screen