Make sure the drivers for the interface are all up to date. Then make sure to select the apollo solo as your interface inside of studio one. If it is not visible to be selected then im assuming its a driver issue.
I have not found any sort of list or post discussing which dsp interfaces, besides presonus made ones, that have integrated hardware low latency (blue z instead of the software green z) monitoring. Stumbled upon your post after spending the last 2hrs looking for any info on that. Hopefully you simply have a driver issue and not this rabbit hole forum scrolling
