Meanwhile, I'll keep play around with the name plate settings - now that I know I'm trying to make changes in the right area - in hopes of finding an answer. I'm not sure if it will be noticed because of that so I'll make a new post if I don't hear from anyone in a few days. I had marked this post resolved but when the problem recurred I marked it as unresolved. I also confirmed by logging to my alt that - for him - health bars, cast bars and debuffs are still appearing. I've included a screenshot of the actual character for whom I'm having the problem and an export of the profile I was using right before I took the screenshot below in hopes that will help troubleshoot the issue. So I disabled every single other addon I had - including WeakAuras which made the fight from the screenshot below really fun - reenabled Elvui and Elvui Options - and started a fight hoping the enemy's bars would come back during a fight. AtlasLoot Enhanced is an addon for WotLK 3.3.5a to show every loot table for every boss, every item set, PvP Items and items for every reputation faction. Then, given the magical disappearance then reoccurrence, I figured it must be some other addon screwing around with things. If it worked for my warrior, it would work for me spriest. My first troubleshooting step was to copy the profile from the alt from the previous screenshot. Suddenly, without fooling around with any settings, I happily had enemy cast bars, health and debuffs. While I was waiting for a reply to this post, my issue magically resolved itself yesterday. As it turns out, my Nameplate problem hasn't been resolved.

Enemy cast bar addon