Expression using REF_ROWS VC is not returning rows as expected. What am I missing?

[WillowMobileSys]

I am creating an expression as follows:

SELECT(Parts[Part ID], IN([Kit], SELECT([Related Ordered Kits][Kit], [Processed?] <> true)))

I am trying to leverage already existing REF_ROWS for better performance.

When using this in an action on Form Save, it doesn’t appear to return any rows. So I began testing with the aid of Virtual Column (VC).

The VC is defined as a List of Ref Type with the base table = “Parts”. Part ID is the Parts table key column.

In the Detail view, the VC shows as below named “Test Kit Count” - indicates 4 rows but no rows are displayed

Clicking on the “View” button, the correct Parts_Inline view is being used but again no rows displayed. This same view is used elsewhere with a REF_ROWS column without issue so I don’t think it is a view problem.

If I change VC List base type from Ref to text, the 4 Part ID values are properly listed in the view.

However, if I click the Edit button to go into the Form and simply click Save, when the app returns to the Detail view the VC (base type as text) is blank initially. Waiting for few seconds, without touching anything else, the VC will update to the 4 values again as shown above.

What am I missing?

Why is the initial expression, when used in an action returning no rows?

Why, when placing the expression in a VC does it show no rows in the inline view?

And why, when the base type is text, does the VC blank out after a Save and then update again with the correct values?