OData V4 Fiori Elements: "KeyPath missing at p.getItemFromContext" when selecting Value Help - Fiori

Hello SAP Experts,

I am facing a persistent UI5 ERROR in an OData V4 Fiori Elements application (based on ABAP RAP).

The Scenario: I have a Root Consumption View with an input Parameter. I have assigned a custom CDS Value Help (Dropdown / #XS) to this parameter. The dropdown successfully opens and displays the data in the Fiori Preview.

The Error: When the user clicks/selects an item from the dropdown list, the slection doesn't happen with the following console error in the browser:

Uncaught (in promise) Error: KeyPath missing at p.getItemFromContext

1. Value Help CDS View (Single Key, Dropdown)

@AccessControl.authorizationCheck: #NOT_REQUIRED
@EndUserText.label: 'Value Help for Parameter'
@ObjectModel.resultSet.sizeCategory: #XS  

define view entity ZI_VH_CustomValue
  as select from custom_domain_table
{
      @UI.lineItem: [{ position: 10 }]
        key cast( domain_value as abap.char(1) ) as ValueKey,

      @UI.lineItem: [{ position: 20 }]
      @Semantics.text: true
      domain_text as Description
}
where active_status = 'A'

2. The Consumption View (Short Version)

@AccessControl.authorizationCheck: #NOT_REQUIRED
@EndUserText.label: 'Main Business Object'
@Metadata.allowExtensions: true

define root view entity ZC_MainBusinessObject
  with parameters

    @EndUserText.label: 'Custom Filter Parameter'
    @Consumption.valueHelpDefinition: [{
        entity: { name: 'ZI_VH_CustomValue', element: 'ValueKey' },

        /* Explicit binding to pass the value back to the parameter */
        additionalBinding: [{
            localParameter: 'p_custom_filter',
            element: 'ValueKey',
            usage: #RESULT
        }]
    }]
    p_custom_filter : z_custom_data_element

  as select from ZI_MainBusinessObject
{
  key DocumentId,
      DocumentType,
      PostingDate
}
where PostingDate <= $session.system_date

My Questions:

1. Is there a known limitation or missing @ui/ @Consumption annotation required to bind a Value Help strictly to a PARAMETER (rather than a standard table field) in OData V4?
2. Why is the OData V4 framework failing to resolve the context for the selected item despite the explicit localParameter binding?

Any insights or workarounds would be highly appreciated.

Thank you!