Ran into some electrical problems. For efficiency I sized the 5VDC PSU to power the USB hubs in addition to the monitors, illuminated switches, etc. Once I started connecting everything I had rolling failures across every system.
I temporarily removed external power from the USB hubs and everything is fine. The manufacturer says the easiest way to combat this is to have a separate PSU for each device – I am asking for clarification (i.e. they mean each hub).
The HUD used a Samsung U70 which is DisplayLink technology. That is wholly incompatible with the rest of the monitors which use MCT. Only recently the DisplayLink installer has warned about the incompatibility but the number of devices I have on MCT outnumbers the devices on DisplayLink.