I just wanted to post an update because this issue still persists. This is a warning for anyone using Wyse terminals. My company deploys about 100 Wyse terminals and we will often use a 22-23″ monitor and sometimes using two. Initially we were getting the issue using dual monitors at native resolutions both 1080. The same black bar. We assumed it was an issue with the cheap monitors. This would also creep up when we were using the included VGA adapter and VGA cables. Well in addition to that issue that really has not gone away, except we switched monitor brands and that minimized the issue along with dual dvi cabling. Now I have had the issue with a single monitor running at 1080 connect via VGA. The monitor is an HP LV2311. Using vga I was missing rendered space both on the right and left horizontally, at the same time. I switched it to DVI and the issue was corrected.
I have tried to work with both Wyse and monitor manufacturers and they all want to shift blame to each other. The only way to quickly fix it is using DVI. Quick warning to anyone buying a wyse terminal.