Same issue. Can't color calibrate the monitor using stock color profiles or otherwise. As the result the monitor is too bright, which completely defeats the purpose.
Update: nevermind me. The issue is
well known Apple bug.
Nothing to do with the USB->HDMI adapter.
Has to do with having two identical monitors.
Has not been fixed since forever.
The work-around is to turn monitor mirroring on and off every time you reboot\relog. Bummer.