Bloodline quest - can't get into castle

I'm playing Skyrim Remastered on Xbox One.

Bloodline is the Dawnguard quest where you free Serana from Dimhollow Crypt and take her to a boat at Icewater Jetty, then on to Castle Volkihar.

My problem is I can't get into the castle. Apparently, Serana is supposed to tell me to "let her do the talking," but she doesn't ever say anything when I arrive at the castle. The solutions I've found so far have been for PC (edit config files) and older console versions (delete the DLC). Unfortunately neither of these will work with these versions ... right? Am I stuck with a permanent second companion?

Edit: I did try loading older saves, but the only choices I had were saves either from after I met Serana or WAY before I met her. I wasn't willing to lose that much progress.

The Bugs section of the Elder Scrolls Wiki page on this quest has a relevant entry:

PC 360 PS3 Sometimes the gate to Castle Volkihar does not open after the gate keeper says his line, or does not say it at all. This can occur if Castle Volkihar is discovered beforehand, although this is not proven, nor has this yet been addressed by Bethesda.

• Fix: Type in console: setstage DLC1VQ02 10. After doing so, select the gate while in the console and type disable. You will be able to continue normally.
• Fix 360: When Serana initiates the conversation about Castle Volkihar while still in the Crypt, finish it as normal and then DO NOT initiate any other conversation with her! Leave the Crypt and go to Volkihar Castle. (You might also get there by swimming instead of fast travel or using the Icewater Jetty.)
• Fix: Use a plate to go through the gate into the castle. The quest will continue as normal.

Of course you can't do the first one, since you don't have access to the console, but the second or third may still work.

The plate one may be your best bet, as you won't have to load an older save.