I just ran into a similar issue. 16R works fine with one laptop, but output crackles with another. The 2nd laptop works fine with other USB mixer / recorders. Both are running Windows 10.
Tried all the suggested suspects and switches to get the 2nd working. Setting UC to 44.1K seems to resolve the issue to run Reaper and play MP3's from windows media player, but can't record at 48K.
Oddly, connect back up to 1st laptop and now it won't play MP3's from windows media player. Reaper seems to work fine though. Solution was to to reinstall the UC driver, power everything down and reboot.
Went through the whole process twice...