I am developing a survey that is to be used to update existing points with water quality data via a related table. All of which is currently hosted in AGOL. I've created a relationship class using Global ID for the site points and a Parent GUID field in the related table. All of that seems to be working as intended, but when I try and submit a test survey an error pops up that says: "Send Error: Object reference not set to an instance of an object."
I have the submission URL set to the Feature Class address that is located on feature service overview tab and the Form ID field set to the related table name.
Any information that is available would be greatly appreciated! Note: the lack of documentation that exists about updating point features is pretty shocking. I would expect this to be a very common use case as many workflows would require the use of updating existing locations with new data....