The cup rim sensor (rocker) on the central spout is not actuated while coffee is being dispensed.
Make sure that the cup rim sensor (rocker) can move freely up to the cup rim.
If the container has a very wide opening that prevents the cup rim sensor from making contact with the edge of the container (e.g. in the case of a very large cup), the drink will be cancelled. Use a different container or position the existing one so that the sensor can detect the rim.