See if this temporary fix will solve the problem. If you have the latest UMIK-2 drivers 5.xxx, revert them to 4.xxx and try again.
Also, check miniDSP homepage, log in to your user account and search for the "Umik-2 Gain Control Tool". Should be downloadable here: https://www.minidsp.com/userdownloads/usb-microphone-series/umik-2