It returned this:

^temp.debug(6492,"size")=""
^temp.debug(9788,"data")=""
^temp.debug(9788,"size")=0
 

Strangely, I recreated that same logic in Powershell using Invoke-Webrequest, and it printed out the json list I'm looking for just fine when I called the API, with a 200 code of success. When I print out the status code in the terminal for the objectscript code, it returns 302, which is a URL redirect, yet they both look as if they have the same functionality.

If I do 

Set stream=##class(%FileBinaryStream).%New()

Write stream.CopyFrom(getStaffReq.HttpResponse.Data)

I get this large output:

v¯fAPI\-e^zCopyFrom+1^%Library.FileBinaryStream.1^1-e^zGetStaffRequest+21^CompBI.bo.APITest.1^1"d^^%Library.FileBinaryStream.1^0,E^zSizeGet+1^%Library.FileBinaryStream.1^1e^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0"d^^%Library.FileBinaryStream.1^0-E^zCopyFrom+2^%Library.FileBinaryStream.1^1e^^CompBI.bo.APITest.1^0"d^^%Library.FileBinaryStream.1^0-E^zCopyFrom+2^%Library.FileBinaryStream.1^1e^^CompBI.bo.APITest.1^0d^^CompBI.bo.APITest.1^0E^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0d^^CompBI.bo.APITest.1^0E^^CompBI.bo.APITest.1^0d^^CompBI.bo.APITest.1^0E^^CompBI.bo.APITest.1^0d^^CompBI.bo.APITest.1^0E^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0d^^CompBI.bo.APITest.1^0E^^CompBI.bo.APITest.1^0d^^CompBI.bo.APITest.1^0E^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^CompBI.bo.APITest.1^0'd^^%Library.DynamicAbstractObject.1^03E^%FromJSON+37^%Library.DynamicAbstractObject.1^1e^^
CompBI.bo.APITest.1^0d^^^