Sorry I meant to edit this. My problem was the Value type I was trying use to filter the data had to be set to integer text. I was trying with it set to number, so no data was returning. Once I set it to integer text I just used the data[collection].userId because it will always return only one result in the array.
However I still have not been able to figure out how to return all results which have a matching userId when some items have only one nested object and others have a list of nested objects. It only ever returns the results with the single. Nested object.
Single nested object:
nested list of objects
There is another thread about this I will try to find it and link to it.
I am pretty sure this is because the filter flow editor by default allows you to define a nested item as an object, so when there are multiple objects under the same node it does not match the object being filtered
This is the thread with screenshots of the filter flow editor