FME Server Error: MAXIMUM_COUNT clause must specify an integer. Value 'None' is invalid

I have developed a workspace that makes a HTTP call then returns the parsed JSON response. It runs from FME desktop successfully, but when published to FME Server as a streaming service I get the following errors:

From the logs it's failing just initializing the workbook and before trying to connect and make the HTTP call. I was unable to find a similar error anywhere else.