As a Vampire Lord I held the button on her so that I could order her to attack something manually. She did that, then I tried to order her to loot the corpse, and she moved there. Now, she doesn't follow me anymore. She just stays there.
I tried issuing commands to her and she does them, but as soon as she's done she just stands there again. Since in that mission she is mandatory to have with you, you can not dismiss her, and you can't talk to her to tell her to follow you again. Anyone got any tricks to how I can solve this?

I tried reloading. I tried exiting the area and coming back. I tried ordering her close to the transition before moving to next area but that didn't help either. I can't continue the questline.

Can't get her to move at all, darn it. And I have no save before that,

So you have not told her to wait, or dismissed her, she is just stuck? Go to one of the way shrines and travel elsewhere, or leave the vale and see if you appears with you. Or if you have a paragon on you try the paragon shrine and see if she will travel with you.

No I used the thing where you hold the action button on her for a second, and you cna give her an order, such as attack, or, as I thought it was, loot, it wasn't loot, she just moved to the location and then she stopped. Now normally when you do this you can talk to your companion and tell them to follow you again, well, she doesn't ahve that. No she doesn't appear no matter where I go to, she stays in the dungeon.

Unless you have a previous save game to load you will have to finish the quest without her then, she should reset before the next quest starts. No matter how you manage it, you do not risk telling Serana to wait or go anywhere during this quest.

Hi Wintermist

This is a known bug with Serena, the good news is its easily fixable.

just take your weapon of choice and beat on Serena until she drops down to 1 knee with low health . After that, she will resume following you as normal...I had her get stuck a few times during the Dg quest line and beating her up until she dropped to 1 knee with low health solved the problem.

don't worry, you can't kill her, she is marked essential. This should fix her for you.

What do you mean "holding the button on her"?

Awesome, will try this!! Thanks!

EDIT: Hmm no that dind't help me. She did grow angry with me though and attack me lol. But exiting and coming back she's not angry anymore. But she still won't follow me.

You can hold the action button (E) on her and through this you can give her commands such as to attack an enemy or whatever. I did this.

Oh ok you're referring to the follower commands? I play on console and you just have to press the activate button when the crosshair is on a follower to bring up the commands.

I had the same problem. I just restarted the game.

It wasn't during an essential quest though, thank god, so I was able to dismiss her. After I reloaded, she was in dawnguard.

I just kept going on alone and she pops up when she's needed and later comes with me back to the Castle, all ended well.

Is this a workable fix for the 'wait' and 'dismiss' issue?

If no-one knows, I'll give it a go and see if it works...being unable to wander around alone is a bit of a svck for rp'ing after dawnguard, particularly if you still like having Serana around at times.

What issue?