I don't know, Reece.
The SI drum patterns are straightforward MIDI loops.
They will play properly through SI, Session Drummer, EZ Drummer, or any other drum synth mapped to GM. However, they must be dragged from the SI interface to a MIDI track.
I can see Drect Show coming into play with A DXi, but I believe SI is a VST.
Does Direct affect those as well?
TL1673, instead of inserting SI Drums as a Simple Instrument track, insert it selecting MIDI Source Track, and First Synth Audio Output.
This will give you two tracks associated with SI Drums.
Your Sound Center track appears to be the Synth Audio Track, but may not have an associated MIDI source track.
Your SI Drums track is set up as a Simple Instrument track. I don't really like these, because you can't see how the signal is being routed.
You should be able to drag the MIDI patterns(loops) from SI Drums to a MIDI track at will.
You can mix and match the loops, or enter drum notes in the PRV, or play the drums via a MIDI Controller for variation.
Also, the notes you trigger with your mouse will not record. This triggers the synth directly, but does not record the notes to your MIDI track, which is essential for playback.