Having market data enabled is necessary if you want to get/stream OHLC prices, volume data, P/L values or other information that is considered market data for non-Forex instruments on the live environment*. By default market data is disabled for all non-Forex instruments which restricts the API from distributing it. Instead you will see NoAccess in response fields.
You can enable access to market data via OpenAPI in SaxoTraderGo by following the steps below.
Step 1 - Log in to SaxoTrader GO
Step 2 - Click Account Tab
Step 3 - Click Other Tab
Step 4 - Find card with label Open API Data Access
Step 5 - Click Enable
Step 6 - Accepts terms by clicking Accept
With this setting enabled you should now be able to get access to market data such as prices via OpenAPI.
*Please note that market data is not available on the Simulation environment. And following the steps above will not give you market data on that environment.