View and Set Metadata in Ngrok

I'm trying to use Ngrok for SSHing into a machine from a different network. This all works fine, but with a script im trying to write, I would like to specify which user has started an Ngrok tunnel, I want to store this in the metadata when launching Ngrok. I have edited the YML file adding metadata : "testUser1" but when I check the tunnels with the API the metadata field is empty. Does anyone know why this is happening, or another way i can get around this? Better yet, when launching Ngrok i would love to just specify the metadata here.