Actually, I can't find anything that's wrong, it all seems to be working correctly. If Construct is doing something like inconsistently copying some properties but not others, please file a bug following all the guidelines.
The issue is that if you edit the very first instance and then delete it, then all future instances use these values. The user is left wondering why it is creating new instances with these random values seemingly 'saved', the preference would be always default in their mind. Also any new instances you create and delete, their values never override this initial deleted instance it is referencing. Sure I can file a bug for what I think is happening.