Media Cloud On Core: Attribute-based pricing using Price Adjustment Schedules does not work in AdvertisingSalesManagementDefaultAdPlacementPricingProcedure

Apply the steps below in order. The resolution covers the two possible root causes seen in this scenario.

Cause 1: Pricing procedure input nodes / variable bindings are incomplete

1. Navigate to App Launcher > Expression Sets and open your cloned AdvertisingSalesManagementDefaultAdPlacementPricingProcedure expression set version.
2.  On the Related tab of the version record, click the row-level menu and select Open in Expression Set Builder.
3. In the Resource Manager, confirm that every variable referenced by the procedure exists and matches the Input Attribute name defined in the corresponding pricing plan step. Required pricing variables for ad placement attribute-based pricing must include USAGE_STD_PRC (mapped to UnitPrice [UnitPrice]), OT_STD_PRC (one-time charge), REC_MNTH_STD_PRC (recurring charge), and UOM (unit of measure).
4.  For every Matrix Lookup calculation step that returns a price adjustment, select the Include in Calculation Output checkbox. For source-target attribute-based pricing the Target Product Name step must also have Include in Calculation Output checked.
5. Open the Price Adjustment Schedule used by the product. Set Type = Percentage and Value = 30 (or your required value), and confirm the schedule is linked to the same Product Classification Attribute (for example Capping [Capping__c]) used by the matrix.
6.  Navigate to Setup > Object Manager > Product Classification Attribute > Fields & Relationships and confirm Is Price Impacting [IsPriceImpacting__c] is set to true on the attribute used in the matrix.
7.  Navigate to App Launcher > Vlocity Calculation Procedures (or Pricing Designer for BRE-enabled orgs) and use the Simulate function on the latest active version of the cloned procedure. Enter sample attribute values matching the line item and click Simulate All Steps. Every output variable referenced by the pricing plan step must return a non-null value; any variable that returns null is the missing input node reported by the Instant Price error.
8.  For each null variable, add the missing Pricing Variable Binding: in Pricing Designer open the variable, set Destination Field API Name to the API name of the field on QuoteLineItem [QuoteLineItem] (for example UnitPrice), and confirm the Output Variable on the calculation step matches the variable Code.
9. Activate the new procedure version and on the pricing plan step set the Active flag to true.

Cause 2: Standard profile can't read fields referenced by the pricing procedure

1. Navigate to Setup > Users > Profiles > [Standard User Profile] > Object Settings > Quote.
2. Grant Read and Edit on every field referenced by the pricing procedure inputs (for example Campaign Country [CampaignCountry__c] and any custom attribute fields on QuoteLineItem).
3. Save the profile and have the affected user log out and back in.