Getting We couldn't complete your request. Resolve the following errors and try again. One or more inputs in action (Apex:Prompt_Program_Recommendation_Invocable) don’t match the required object type. Update your input types and try again. Sender error

Same for me! So frustrating. I found a blog that was guiding users on this, but it was showing an older version of Prompt Builder, where there was a prompt type called "Sales Email",...which doesn't exist anymore - so I'm using a Flex.  

Still doesn't make sense. Same as you, tried, entire resource, id, email, name, etc. Nothing works.  

FYI - This is not an answer but to support need for an answer!