I tried in Slave Thru mode and it doesn't transmit to the PX at all. What should the PX be set to? I currently have it set to Slave via MIDI din and then Slave Thru via MIDI din and nothing works.
What’s your Tempest Midi clock out cable settings?
From the manual:
MIDI: Clock OUT Cable: None, MIDI Port, USB, MIDI•USB—MIDI Clock data can be sent out via the MIDI Out port, the USB Port, or both MIDI and USB. If “None” is selected, MIDI clock out is disabled.