SCENARIO: You’re trying to automate creation of Opportunity Product’s based on existing products.

PROBLEM: The “UnitPrice (only one of unit price or total price may be specified).” error is preventing the flow from completing.

ROOT ISSUE: Salesforce is assigning field values beyond what is defined in assignment elements during record creation. This only appears to happen when “How Many Records to Create” is “Multiple”.

SOLUTION: While not ideal as it is not as efficient, an Opportunity Product record must be created with each loop and the field values assigned in the single record create element. This method restricts the record creation process to apply only what is defined in the Set Field Values for the Opportunity Product section which is critical to ensure Sales Price (UnitPrice) and Total Price are not set at the same time.