So in my earlier video I introduced concept of "priming" the rhythm.
• Zoom G5n: Remote Control Rhythm
I now realise that what I am doing is moving the view window!
We have to make the rhythm visible under a footswitch ie FS1 .. FS4
Then we "press" the FS with sysex and it works.
I forgot that tempo is global not per patch. Likely I knew it here - but forgot.