I tried starting a new character today, and I found that when you get to the storeroom in Helgen Keep, there are no enemies waiting there to fight. Whoever you chose to go with (Ralof or Hadvar), walks through the empty room, goes to the door at the end, and just stands there. When you talk to them, they just give generic responses, like "we'd better keep moving." They never say to search through the barrels for potions and supplies, and there is never a quest prompt to do so either. I found that you can just go out of the room without them and continue on, but the rest of the Unbound quest is basically stuck in that storeroom, and does not advance. For example, in the torture room there are no enemies waiting for you to fight. If you picked Ralof, there are two Stormcloaks there, and the torturer and his assistant are already dead when you arrive.

I tried restarting the game, and starting a new game, about half a dozen times. The same thing always happens. It does not matter whether it is Ralof or Hadvar who I go with. They both get stuck at exactly that same place. I have tried using the wiki to manually advance the quest, and can get the game to give me the prompt to search the barrel for potions. But that is as far as it will go. Ralof and Hadvar remain glued to the spot. It cannot be a mod conflict, because I disabled all the mods I had and tried it with a vanilla start, and still had this bug.

Has anyone else had this issue?

I found an old save from another character at the beginning of the game, and it works fine. I get to the storeroom and there are two Imperials in there who attack (following Ralof). Then Ralof prompts me to search for potions, and goes out the door with me. So I can still play the game normally. I just had to use the showracemenu command to change my character. But it would be nice to be able to start a brand new game sometime.

I have this very same problem. Along with this problem, the draugr boss in bleak falls barrows does not drop the dragon stone. Be sure to watch out for that. I do not know what is causing this but it sure is aggravating.

Well it is nice to know I am at least not alone. I wonder if it might be an issue from one of the patches? I can go back to older saves, and Ralof/Hadvar act normally. So I will just make sure to keep those, and start every new character from one of those saves, instead of starting an actual new game.