Is API background=true still working?

I’m attempting to run the following Mock API Schema

schema "Get_Host_Detail_ResourcesJSONOnly"
temp = generate(50000)
schema "Get_Host_Detail"
data = generate(1)
data['resources'] = temp

By calling :

I get the result

“error”: “API requests are limited to 5000 records per download.”

It works when I use 5000 or less in the first generate call. I tried commenting most of it out and calling just the first generate(50000). Same result.

I have a Silver plan.