[digi98]

I did have HDMI Audio enabled to the Monitor (which has an audio output jack, but no speakers unfortunately ;(.

This could have been the cause, so I disabled that and will have to try a few more tests with hdmi audio disabled and report back.

Ideally, would be nice to know if it's possible to keep hdmi audio to monitor on so we could send windows sound to monitor via HDMI instead of to PT I/O device like Scarlett.

I didn't even know speakers in hdmi monitors was a thing - sales guy probably could have upsold me at the time if he had 'em, though with my luck they'd probably end up impacting performance with the PT/Scarlett combo anyway, especially with the sample rate change tango.