Opened the OBD app, and connected to the bluetooth device. It automatically went to the combined mode and started recording, as per configuation. Great! However, I failed to notice that the GPS was turned off, and my travels were recorded without GPS data, rendering them mostly useless.
The app should check that the GPS is turned on before proceeding. Could either automatically turn it on (my preference), or ask for confirmation (non-preferred option - it's just one more annoying question).