Thank you for the quick reply. The MIDI monitoring app was useful to confirm the H90 was sending CC#1 out.
In the end I figured it out. For info, I had two issues….
1) In Cubase I needed to create the H90 as a remote MIDI device and assign a so called Quick Control to CC#1. Once that was done Cubase recorded automation when using the expression pedal.
2) The second issue, if you one can believe it, was due to not one but two faulty MIDI cables. Go figure. Once I replaced them both with a third one the input back to the H90 started behaving too.
Off to create some weird sounds now.
Thanks again!