This is a problem I've been having the entire time I've been trying to do the dawnguard quest. Every so often after a fight, she would just not move anymore. She would sheathe and unsheathe her weapon when I did, would stealth when I did, and would even talk to me, but she would not move. I used to fix this by simply 'killing' her, but now for some bizarre reason even that doesn't work. I've tried to look up other solutions, but they don't work either. I've used my 'voice of the emperor' power on her, with no effect, I've even used the moveto player command, but it doesn't work. Yeah, she's even immune to console commands. And I did use that command once before to get Hadvar unstuck (in the same run-through I believe). All using the command does for me is make my character jump up for a second for some reason (Hadvar immediately appeared next to me when I did it on him). Even disabling her and enabling her again doesn't work. Oh, and waiting an hour doesn't do anything either.

And no, I don't have any shouts (I've avoided doing the main questline, I haven't even done bleak falls barrow). But from the looks of things, it wouldn't help anyway.

She also has no dialogue for following. I've tried to tell her to 'split up', or w/e, but that of course does nothing.

She does normally follow me around, but every now and then, right after a fight, she gets stuck. And this time, she refuses to fix. Its been a constant annoyance.

And no, I can't fast-travel. I'm inside a cave that I can't back out of (its one of those caves where you're thrown into an area where you can't get back to the entrance except to complete the cave). So, I would actually have to complete a quest cave all by myself just to get to a point where I might be able to fix her.

I'm honestly starting to think my game is bugged. I had something like this happen once playing oblivion years ago, but that game was full of bugs. Right at the start, when the emperor walks up to you, one game he just fell right through the floor, and left me stuck against the wall unable to move. I was able to fix it by loading the auto-save, but after that I was encountering all sorts of bizarre bugs, the only one I can remember is Armand actually falling through some steps and getting stuck, making it impossible for you to start the thieves guild questline, bc he was unable to move from where he was! I told people about this, and they told me I just had a corrupted game and had to start over, which I didn't mind since obviously I had made no progress in anything. But this Skyrim game I've had no problems like that. Hadvar getting stuck and serana getting stuck repeatedly have been my only problems. I've had no other followeres besides those two, so I don't know if its just followers in general or not. And no, I have no mods that change followers at all. The mods I do have are frostfall, eat-drink-sleep-bathe, skse, skyui, a matter of time, tales of lycanthropy, werewolf sound and texture overhaul, a mod that makes werewolves occur in the wild, and today I just installed the organized bandits mod, but my follower problems were occuring long before that.

Oh, and this game, it might have something to do with the fact that I told her to wait in an inn, but when I left the inn I forgot to tell her to follow again. I don't know if she followed me all the way to the cave, but obviously she was in it when I arrived. But I don't think she followed me to the point where I fell into the river and got swept down several waterfalls. She did appear when I finally landed, and helped me kill some spiders, but she won't move any further. I didn't notice this until I was fighting a giant spider all by myself. And she has no dialogue for 'follow' or 'wait'. All she has is the inventory option, the split-up option, and a dialogue option related to my current quest.

Am I just going to have to abandon this save? I got to about this point before in the questline, but quit because I was using a weird paladin build which wasn't very practical (the fudgemuppet one that has you wearing no armor, wielding a warhammer, and relying primarily on restoration to keep yourself alive, when you're wielding a two-handed weapon). The build I'm using now is of my own design, and does actually work. I'm not too happy about having to re-start my game, again. If I have to I'm not even going to try to do the dawnguard quest ever again, that questline is obviously jinxed for me for some reason.

I managed to get the moveto command to work for her, I clicked on her and it gave me a completely different refID from before, I don't know why. I was clicking on her before, with her standing right infront of me. Maybe I was selecting a monster on the ground or something?

Whatever, anyway I managed to get the moveto command to teleport her to me, but she doesn't follow. She just stands there and wanders a bit. I'm thinking the problem may be that she's not set to follow, but I don't have the option to change that, and I can't find any console commands that will let me change it manually.

Another update: Apparently the reason I couldn't select her before, was because I had candlelight on. If you have that on, clicking anywhere on the screen will give you a code which doesn't correlate to anything.

I also found reference to some code that resets her, but even that does nothing. The console command is:

setpqv DLC1NPCMentalModel LockedIn_Var False

Typing this in exactly does nothing. Its supposed to maker her dialogue options reset or something like that.

edit: I found the problem. When I entered the console command, I wasn't supposed to capitilize 'var'. After I typed it in right (as var rather than Var) then the option to tell her to follow me showed up. Now, she's working fine. Let's see how long that lasts.

Because you've tried several commands I'd recommend reloading an earlier save. However, if that is not feasible try to change zones, that is, go from inside to outside or vice versa. Perhaps she will zone in/out with you as she should and reset.

P.S. Since you're in a cave in/out would me transition within one zone of the cave to another if it has them.

A Bit of unrelenting force should do the trick.