Hi 
I have a scriptable object, that references another object, which is in effect a tree of objects.
I’ve added [System.Serializable], [SerializeField] and [SerializeReference] according to the documentation, but my object is still not being serialized, and with no error to go by, I can’t figure out why.
Is there a way to debug which part of the serialization that’s not working, without commenting out all code in a bunch of classes and removing // one field at a time?
Maybe show your code here. Unity will simply not serialize any fields which are not serializable, but the other fields will be serialized. If your whole object isn’t serialized it either has no serializable fields or is itself not serializable. Maybe share your code here?
Yea, turns out my coffee was too weak today. 
I added [SerializeField] instead of [field: SerializeField] to my properties. after adding the “field:” it serializes everything that is serializable and I can easily go through the missing parts and fix as needed.
Thank you for pointing me in the right direction.