Hi bobn,
there are 40 so called "+Audio" Styles on Tyros5.
If you use such an Audio Style, the main Drum Part is AUDIO and cannot be recorded by doing a MIDI recording.
There are two options you can do:
1. Use the Audio Recorder
2. If you use the MIDI Recorder, the Audio Drums will not be recorded (but only a few individual MIDI Drum sounds, like crash cymbals, which in addition to the Audio Drums still sound on channels 9 and 10 of certain Audio Styles.
When you play back the recorded MIDI file, you will not hear the main Drums. So, make sure that ACMP is OFF, and also make sure that the same STYLE is loaded that you used for the MIDI recording before. Now, while the MIDI Song is playing, additionally start the STYLE. The MIDI file will automatically control the STYLE in the same way you have played it when you recorded the MIDI file. (You can also use any other Style, and have it automatically controlled by the playing MIDI file.)
If desired, you can record this using the AUDIO Recorder now.
P.S.
It is not due to copyright as suggested by Toril, but, as mentioned, the Audio Part of the Audio Styles simply cannnot be recorded as MIDI data.
Hope this helps!
Best regards,
Chris