Acer Switch 11 :: Contrast Adjustment Not Working Consistently

I recently purchased an Acer Switch 11.  I noticed that I wasn't able to adjust the display contrast, using the left/right arrows and "FN" key.  Through a chat session, an Acer technician recommended that I reinstall the Intel VGA Driver through Acer Recovery Management.  I followed his instruction, and it worked.  However, later I noticed that I could not longer adjust the contrast.  I could see the indicator move up and down in the upper left-hand corner of the screen, but the contrast wouldn't changed.  I once again reinstalled the Intel VGA Driver, and it corrected the problem.
 
After re-installing the driver a second time, I decided I would leave the tablet plugged into the keyboard.  Every fifteen minutes or so, I would unplug the display to see if the contrast changed.  Based on my settings, it did change as desired.  I did this for several hours.  Later, I decided to remove the display from the keyboard.  Initially, I was still able to adjust the contrast.  However, after 10 minutes or so, I no longer could make adjustments.  At that point, I placed the display back into the keyboard dock.  I tried to see if it being locked into the keyboard was required in order to make contrast changes.  It still didn't work.  I then reinstalled the Intel VGA Driver and corrected the problem.  I have kept it plugged into the keyboard, and I can still make adjustments.