SureAI

I have a custom follower that only has "Skyrim.esm" as a dependent. It works fine when importing her into Enderal.
This is the original mod: https://www.nexusmods.com/skyrim/mods/83958

The problem arises when I tried to use the patched version I created to address bug with the original mod:
https://www.nexusmods.com/skyrim/mods/105073?tab=files

The 0.05.00 patch version works. I can use Summon and talk to her as a follower. In the later versions of the patch I added Dawnguard to add "PlayerIsVampireRace" conditions to a few dialogues and Dawnguard ingredients for a future feature. I already know that followers cannot be Skyrim DLC dependent. I removed all the Dawnguard specific edits, removed Dawnguard as a dependent, and even ran it through TES5Edit to make double sure it was cleaned. Despite it being clean I'm unable to summon her in Enderal. I can use "Player.PlaceAtMe" to produce a clone but the clone doesn't even speak. If the clone can't speak that means the original wouldn't either.

Why is it that once a DLC master has been added that Enderal has problems with it functioning? Is there something in the ESP that Enderal checks that considers these mods invalid? I'll reiterate that I manually removed all the DG edits so there's no reason it shouldn't work in Enderal. I can provide you with a cleaned up version so you can compare it if need be.

Sorry, i don't know the mod or the patch, so I can't really help.

but:
The Dawnguard-DLC is very bad at Enderal, so anything based on it is incompatible.
The file Skyrim.esm is also not the same as for the game Skyrim, it is very different.
So this mod must be completely modified for Enderal. Check everything the mod wants to do.
Only change what is absolutely necessary and watch out for possible errors.

So no matter what you do with it, always save with a manual savegame before installing a mod and then change what is necessary.
(or use another mod, if needed)

PS:
Unfortunately we don't test or support any mods or bugs, that result from this. The same goes for own changes or any cheats.

I got it figured out. I had to set the newly added quest aliases to Optional and Allow Dismissed so it would allow the main quest controlling the follower to initialize.