I can't access chapter 25. Can someone please help?

I am just before the wedding between Calista and Zael, after chapter 31. The maids are all getting things ready. There is no pacing knight on the second floor. There are no knights in the Underground Depths.

I think I did talk to the two knights guarding the giant door in the Underground Depths. They asked me if I wanted to do something, to which I declinded and figured I would come back to later.

Also, I have been told by Lazulis Knights and people online that I can't come back to town after I progress the story. So I just want to cover my bases.

What can I do? This is very frustrating? Thanks in advance for the help.