From the screenshot I uploaded you can see I have tidyplates activated on friendly players and all npcs. It works for players, however it doesn't seem to be working on npcs! Only when I have them selected/targeted like "Scott" in the bottom corner does it activate. Wondering if this is a tidyplate issue, maybe I'm missing a setting to turn on or some sort of limitation of the game? Thanks!

Edit:

Also noticing it won't appear on "enemy" players from opposing faction. It does show up just fine though with open world enemies though!

And just in case, I do have these options selected in my interface:

With the way that nameplates work we aren't really able to create new ones for units that don't have them in the standard blizzard UI. So since they won't show them for friendly NPCs that aren't targeted, we can't either.
Important to note here that there's a difference between a "nameplate" and the name that appears over some units. In the last screenshot you made you can see the Names options in the top half and then the nameplate options in the bottom half. We are only really able to modify the stuff that the bottom half shows. As you can see there, there aren't any options to get blizzard to show you nameplates on all friendly units, just enemy units and friendly players (and your current target also gets a nameplate).
I'm not super sure how exactly enemy players work. If you have warmode active it should show you a nameplate over all of them. If you have it disabled it doesn't show me one over some. Maybe it has to do with them having pvp on/off?

So I think the extra nameplates you would like to see can't be added by addons unfortunately. If you're in a situation where you'd like tidyplates to show a nameplate on some unit and it doesn't, but the normal blizzard UI (or some other nameplate addon) does, then that's something I can definitely work on making happen though!

Thanks for the info about using Kui nameplates. I checked what they do and it's that there is a CVar that they let you enable that Blizz's UI doesn't. One of the features I want to add is a cleaned up options menu and I've added this to the list of things I need to add.
In the meantime, if you want to keep using TidyPlates without Kui, you can paste this
/run SetCVar("nameplateShowFriendlyNPCs", 1)
to enable them and
/run SetCVar("nameplateShowFriendlyNPCs", 0)
to disable them in your chat window or a macro.

Thanks for the info about using Kui nameplates. I checked what they do and it's that there is a CVar that they let you enable that Blizz's UI doesn't. One of the features I want to add is a cleaned up options menu and I've added this to the list of things I need to add.
In the meantime, if you want to keep using TidyPlates without Kui, you can paste this
/run SetCVar("nameplateShowFriendlyNPCs", 1)
to enable them and
/run SetCVar("nameplateShowFriendlyNPCs", 0)
to disable them in your chat window or a macro.

Ah, yeah, my husband ended up figuring out it was the CVar that was essentially "fixing" my problem with Tidyplates. I appreciate the macro and I'll hold onto it for now. I am still using TP so I'd love to see this sort of feature added in the future. It's my favorite so I appreciate that you picked it up after the OG author stopped updating it! Thanks so much for being so responsive and I look forward to future updates :) 👍

With the way that nameplates work we aren't really able to create new ones for units that don't have them in the standard blizzard UI. So since they won't show them for friendly NPCs that aren't targeted, we can't either.
Important to note here that there's a difference between a "nameplate" and the name that appears over some units. In the last screenshot you made you can see the Names options in the top half and then the nameplate options in the bottom half. We are only really able to modify the stuff that the bottom half shows. As you can see there, there aren't any options to get blizzard to show you nameplates on all friendly units, just enemy units and friendly players (and your current target also gets a nameplate).
I'm not super sure how exactly enemy players work. If you have warmode active it should show you a nameplate over all of them. If you have it disabled it doesn't show me one over some. Maybe it has to do with them having pvp on/off?

So I think the extra nameplates you would like to see can't be added by addons unfortunately. If you're in a situation where you'd like tidyplates to show a nameplate on some unit and it doesn't, but the normal blizzard UI (or some other nameplate addon) does, then that's something I can definitely work on making happen though!

Thanks for the quick reply! So I did some testing and troubleshooting because my husband also uses tidyplates. We compared settings to match exactly one for one via Tidyplates (in the Damage profile) and the Interface. We found that his was working just fine but mine was not. I did a reinstall of Tidyplates and it still didn't work. I also disabled all addons except for Tidyplates, as did my husband, and his Tidyplates showed NPCs nameplates just fine while mine did not load it unless I targeted. I really am at a loss here at what exactly is going on?

Here is his UI in comparison to mine in my initial post. No addons (other than Tidyplates) were enabled when this screenshot was taken.

EDIT: I ended up installing KUI nameplates alongside Tidyplates and that ended up fixing it. I appreciate your response!

This might be a dumb question, but are you sure both you and your husband are using the same addon and the same version? Tidyplates was essentially abandoned for a few years before I picked it up now and a couple other people made their own addons from forks of it (e.g. ThreatPlates).

If you are using the same, current version of this addon, I'm gonna need a bit of time to figure out exactly what is going on. To be honest, I'm not super familiar with this part of the WoW UI myself so I don't really have a fix in mind right now, but I'll try my best to find the issue.