I’m getting the same issue, and my save was from the latest update.
Viewing post in Cantata Chapter 5 is Live! comments
The latest update (before today) was chapter 4. You could NOT have played chapter 4 on an old save. If you’re having this issue now, you would have had it then. Nothing has changed in the code between chapter 4 and today’s update. The issue described above is due to trying to play an old save made before the chapter 4 update. I explained it in 3 different devlogs:
https://firfireweed.itch.io/cantata/devlog/1081452/cantata-chapter-4-is-live
I should've specified that I played the latest update publicly released on itchio because I remember having to restart because of another previous update that wiped all save data. I download my saves on mobile. I don't know if that makes a difference, but I think I'll just wait later down the line to replay.