Is there a limit to how deep you can save something?

I have a tree structure of data that I am using to store data.

The Top level data is a Scriptable object that is saved into the project, and the tree data itself is stored as serializable classes that have an unknown number of children (ye old N-ary tree).

This saves completely in Unity when I create the object, and change scenes and play. The data is all stored and completely fine.

When I reopen the project after closing however, I find the data truncated to a depth of 8.
Is this a known limit to Unity’s serialization system?

root/1/2/3/4/5/6/7 is saved.
All of 7’s children are lost.

Sounds a bit weird. There are no limitations like that as far as I know it.