After I upgraded to Grails 3.3.0, I noticed that my scaffolding BookController was throwing exceptions. I narrowed it down to the presence of non-empty one-to-many relationships for Book.authors, Book.titles, or Book.years. All of these are embedded objects of type String or Title. When the fields are empty, everything is fine. But the moment any one of them has even a single value, the scaffolding code chokes on them. There is no problem with the relationship between Book and Review because the scaffolding is ignoring it altogether.

Switching from web scaffolding to REST with JSON output does exhibit that problem. Other than still not showing reviews, that is.