Cannot See Additional Fields from Lookup Column When Using JSON Formatting in SharePoint Form

Question

I have JSON formatting applied to a SharePoint form, and I cannot see or select the additional fields from the lookup column.

• List 1 contains [Assets]. date purchased, prices etc.
• List 2 contains [Asset Maintenance] history and references list 1 via a lookup column
  • Select asset by [AssetName] (A calculated column)
    • When selection is made, additional columns [PurchaseDate] and [PurchasePrice] are also selected by default
      • Both List 1 and List 2 have JSON formatting applied to the form header and body

The Problem.

In list two Asset Maintenance, I can see all three columns in the list view.

Once I open an item the PurchaseDate and PurcasePrice no longer appear.
They do not appear when the item is opened or in details view.
Nor as options when I go to Edit Form > Edit Colum

Asset Name = Calculated

Purchase Date = Date

Purchase Price = Number

I have tried adding the following fields without luck in the JSON for the section.

Is it definitely possible to show the additional fields? Should I have customised using PowerAutomate instead?

Thanks
Marty

        {
            "displayname": "Stock Opportunity Details",
            "fields": [
                "AssetName",
                "AssetName.additionalFields.PurchaseDate",
                "AssetName.additionalFields.PurchasePrice"
            ]
        },

Answer 1

Based on your original post, I understand that additional fields of lookup column do not show in the items form.

It's by designed. Because values in additional fields of lookup column are based on values in lookup column, so these filed are read-only.

In addition, this behavior cannot be changed through JSON.

As a workaround, in the items form, click Customize with Power Apps, then save and publish the Power Apps form to SharePoint.

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