Hello there, i'm having this issue, after entering the Fort, listening the whole conversation between Vigilant Tolan and Isran, then talk to Isran, join him, then he introduces me to Tolan and talk to me about going to Dimmhollow, the problem starts here, i went to Dimmhollow and i just founf 3 wolves as enemies, the entrance to the other part of the cavern is blocked by rocks, and the chain is not there (next inside the tower) (it was on a previous playthrough) so can't get into the puzzle area where Serana is. i tried "TLC" to pass the rocks, made my way to Serana's prison, and as soon as i free here, the only dialog option that appears is "Come to me" nothing more, just that, she doesn't talk to me nor follow me, she just stand there, i loaded a previous save, after leaving fort Dawnguard and noticed that Tolan never leaves the building after finishing his conversation with Isran, i can see him going through the exit door, but when i go out of fort he's not there, and he doesn't show up on Dimhollow (so i backtracked the bug which seems to start there, Tolan being the cause). I tried moving to him "player.moveto" and it send me back into Dawnguard fort, next to the exit door, but Tolan seems not to be there so.. basically he just dissappear after leaving Dawnguard fort, i tried to move him next to me, though the command seems to work, he just doesn't spawn, i tried "resetai" tried placing a new one "player.placeatme" and he just says "i'll meet you at Dimmhollow" be he just stand there, i've waited a month, and nothing, so basically i'm unable to start the Dawnguard quest, I don't have any mod that mess with Dawnguard, or Vampires, Serana, norhing, nada.

Edit: I've managed to get Isran and Tolan out of the fort to Skyrim by transforming to werewolf while they are speaking, toggle god mode and let them follow me till the entrance to skyrim/Dawnguard Fort, then change back to human, talked to isran, started the quest "Awakening" out on the field of skyrim, (same events happens as in Dawnguard Fort) now this time i thought in following Tolan walking to Dimhollow (yeah i know long trip) still he went into riften, i entered as soon as he did, and at the other side (inside Riften) same bug, my crosshar was pointing next to the door and it was labeled as "Tolan" pressed "E" to talk to this... invisible Tolan.. nothing happened, moved the crosshair, put it back again and the invisible Tolan wasn't there anymore, well actuallyi think he never made it into Riften, somehow the NPC dissapear after entering another cell, so... any suggestion? anyone?. anyhelp would be appreciated. thx.