You likely have the inputs, outputs, or both connected to the wrong MADI card.    The easiest way to verify these are connected properly is to insert a signal generator and buss to RMU Input 11 with the Atmos Panner inserted below the signal generator.   The signal should meter on the RMU Web UI meters. This can be further verified by bringing up the RME mixer on the RMU itself. If panning the signal to the Z-axis with the default 7.1.4 room results in  audio in the floor channels,  the output is likely connected to the 2nd MADI card instead of the 1st MADI card which is used for monitoring.