Thanks for answering!
I have a MacBook Pro Retina 15"... That being said, I have tried to run X-Plane at all resolutions beginning at 1024x768 to see if the problem was with the retina screen.. No avail.
I also figured that maybe the native screen resolution was the problem, so I ran at reduced resolutions on lower res external monitors... No avail.
I noticed that the Zebo 737 shows the correct (useful) EHSI screen graphics at all resolutions and screens...