Hello Steve Webber, thanks for reporting the issue and providing a reproducer!

Entity 1 has a one-to-many relationship on Entity 2, mapped by Entity 3

This is not a valid mapping. In your example project, TableOneEntity's associated collection twos is mappedBy a property of an unrelated type (TableThreeEntity). This cannot work as the property in the owning side of a bidirectional association (TableTwoEntity) which is referenced mappedBy must be of the same type of the inverse side of the association (TableOneEntity).

You can find more detailed information in the User Guide.