Add GUID field to existing AGOL Survey123 feature layer — Field not auto-populating?

Bud

I have a Survey123 feature layer that was created using the Survey123 wizard.

I need a custom auto-populated unique ID field, so I've added a GUID field using AGOL > Data > Fields. This is the resulting field:

Problem:

When I create new features in an Experience Builder app using the Editor widget, the new GUID field is not being populated. Why isn't it being populated?

Use Case: 

Auto-populate unique ID field in hosted feature layer (common ID between copy/pasted features in ExB)
I need a custom unique ID field so the values will be copy/pasted into a new feature in a different feature layer. The ExB editor widget matches fields in the source layer (the Survey123 layer) with fields in the destination layer, where the field names are an exact match. I can't use the OOTB OBJECTID or GlobalID fields from the source layer, because the destination feature will get new values in those fields, not the values from the source feature.

MobiusSnake

GUID fields don't autopopulate, they default to null.  They're typically up to the application or an editor to set.

You could make a hidden field in your S123 form for the question and use the uuid() function to populate it.

Alternatively, you can use the Admin REST API to create the field with a NEWID() default value, with the Add to Definition endpoint of the layer.  It may be possible to update an existing field's default value with this as well, but I haven't tried it.  This will make the field autopopulate with a new value in the same way that Global IDs are autopopulated:

{
  "fields":
  [
    {
      "name" : "MyID", 
      "type" : "esriFieldTypeGUID", 
      "alias" : "My ID", 
      "sqlType" : "sqlTypeOther", 
      "length" : 38, 
      "nullable" : false, 
      "editable" : false, 
      "domain" : null, 
      "defaultValue" : "NEWID() WITH VALUES"
    }
  ]
}