In addition, I am finding that once I have all 6 monitors working, I can put the monitors to sleep (not HD sleep) and they will come back without an issue. If I restart the computer or shut down and boot up immediately, there is not an issue. If I shut down for approximately 5 minutes or more, the MST hub monitors will not come on. By shutting the computer down and cycling the power to the MST hub, then booting up the computer, I will get my 6 monitors back.
To get all 6 monitors working initially, I need to plug in only the MST hub monitors. Once up and running, I will then plug in each additional non-hub monitor one by one.