I know it sounds stupid, but uninstall it and load the drivers from the device manager manually and then power down and plug it in. Sometimes that fixes issues like this.
Also, be certain it is loading a real driver. If it is loading a "Generic" driver then that can cause such issues.
Also, you may want to try messing with the monitors configuration. You know, the menu on the monitor controlled by the buttons on the monitor itself. Perhaps it will work properly if the color calibration is reset or tweaked?
It has multiple connectors on it. Have you tried each? If it only happens with one or a few, then it may be possible to work around the issue.
I am just shooting blindly here. It could also be gremlins...
Good luck with it.
I quit. I am not coming back.