Service Request error only on REST call

I have an orchestration working perfectly from Orchestrator - this crosses versions from the older version with the separate Orchestrator Client to the more current Orchestrator that has the Client functions built into Studio itself.

My problem is when making an external REST call.  At first I got an error that appeared to be a formatting issue for inputs:

"PODoc" : "234237"

needs to be submitted as:

{

"name" : "PODoc"

"value" : "234237"

}

Now I'm getting:

{ "status":"ERROR","message":"ServiceRequest Ack_Exist: Message: rid is Required","exception":"Exception","timeStamp":"2020-04-24T12:57:22.987-0400","userDefinedErrorText":""}

It's progress because the orchestration is being called and seems to be successfully starting only to halt at the third step with an error not received when testing from the Orchestrator.  Are there any resources to track down/troubleshoot errors that only appear when making calls directly via a REST service?