clearly something is wrong with your hardware (either mainboard or the sound card). you can't blame the software driver as it's working properly for us.
It's a brand new HP Envy X360 Ryzen laptop, and the Xonar works fine on another PC (Win 7). Could be some incompatibility with the AMD motherboard I guess. I've noticed the software (and possibly driver) looks identical to another identically specced soundcard (the Sewell Soundbox Pro aka Diamond Xtreme aka SIIG HD aka Maplin HD) so I may try and play around with the drivers for that.