Does Ionic Pro Build force 'prod' variables?

I have three separate platforms : ‘dev’, ‘staging’, and ‘prod’; each has its own set of APIs, the selection of which are controlled by appending --dev, --staging, --prod to ‘npm build’. When I build locally, all is well.
I get a www configured for the appropriate platform. When I build in Ionic Pro, I always get a ‘prod’ build. Any thoughts on what would cause this?

Thanks for the guidance.