Hello Ben,
There has been some fundamental changes in DisplayLink driver with the anniversary edition. We now use the native capability in the OS to get pixels.
Before, we could do pretty much what we wanted (at extreme maintenance cost) and we enabled Clone/Duplicate on platforms not advertising supporting it.
Would you please check which primary graphics card driver you are using?
If they are older (like for Intel 4th gen), then, they are unlikely to implement the WDDM 2.0 standard which makes "DWM Clone" feature compulsory when it is option in WDDM 1.3 drivers. DWM Clone allows to clone screens across graphics adapters... and now you will see that DisplayLink is a graphics adapter in Device Manager.
The hard dock you have are plugged in to the primary graphics card, so they don't need DWM Clone feature.
Without logs, any version number or date, I cannot give you a definite answer, but, with the information I have, it sounds like it's what you are observing.
When discussed with Microsoft, they explained the only way is to use new graphics drivers. You are unlikely to find recent Intel driver executable validated by the laptop vendor if these are not recent machines.
But here is how you can manually assign the .INF to bypass the OEM check:
http://www.intel.com/content/www/us/...000005474.html
If you wish a more definite answer, I would welcome the log files gathered as described in my signature.
Kind regards,
Alban