I'm using the Workflow REST API based on the example workflows @████████ provided in the following discussion and noticed something.
Discussion: Will Laserfiche ever get a unified, "RESTful" HTTP API? - Laserfiche Answers
The workflows are being invoked as expected, but I recently noticed that the Initiator SID value wasn't being transferred over.
My model was getting the value and it was being correctly converted in the JSON body, but it just wouldn't show up in workflow.
The examples Sam provided worked perfectly, so I took a closer look and realized that the parameter is actually mispelled in the Workflow API itself.
In the API/documentation it shows as "IntiatorSID" instead of "InitiatorSID" which explained why my model wasn't working.
When I renamed the property with the same typo in my integration it transferred over.