Sounds like a problem with the layouts not having the correct flows and/or players assigned to them. Go to Setup mode and check what each layout says it has assigned to it, by clicking it in the Layouts list and seeing which checkboxes are on in the Flows and Players panel (I’m guessing none).
This happens because of a bug that causes your saved layout options to be applied incorrectly. To stop it affecting future projects, delete the files whose names start with layoutOptions_ that you find in ~/Library/Application Support/Steinberg/Dorico.