I have the same issue as posted here which i believe is related to this issue.
My specific use case is related to a slightly different issue i’ve discussed here
Where i need to be able to filter a model collections view with a fitler set on the left hand nav, for a model that is set to display as a tree view. Which i’m looking to solve by writing an API call to create the filter in code, rather than the UI which is currenlty impossible for treeview displayed models.
Great news everyone! 
Deep filtering on GraphQL Content Delivery API has just shipped in public beta!
As the annoucement says:
We have released Deep Filtering in public beta so that you can try it out and see if it meets your needs. We will collect feedback over the next month and make any necessary changes before releasing a final version.
We strongly encourage you to give Deep Filtering a try in a sandbox environment, and send any feedback or issues to support@datocms.com.
Happy filtering!
