Since patch 3 Mizora has been bugged to respond with telling your character to go to Gortash's coronation, even after going to it. This bugs Wyll's quest in act 3.
One fix is to remove the patch 3 hotfix and patch file from the data folder, which allowed her to properly respond to my character. However upon doing so the game crashed mid-conversation.
Links to other people with this problem:
https://steamcommunity.com/app/1086940/discussions/0/3880470363417385579/https://www.reddit.com/r/BaldursGate3/comments/16pmjsl/bug_with_mizora_cant_progress_wylls_quest/