Apparently the iGPU Multi-Monitor setting under advanced/system agent configuration/graphics configuration needs to be turned on. This is labelled for being for virtu but is necessary for the integrated GPU to be detectable by windows, even if you arn't running virtu. This setting is still around on more modern intel systems - with my z390 and 9th generation intel processor its still an available option, and it worked exactly the same on my old box through windows 8-10
Obviously the location of this may vary with different motherboard brands and the name of the setting may be different.
My guess is since lucid logix uses both GPUs, it tells the motherboard to simply run both - independent of whether you're running more than one monitor (with lucid outputting what you're rendering on the dedicated GPU to the integrated GPU), or using a multi-monitor set up taking advantage of both the IGPU and Dedicated GPU as independant outputs without lucid.
In my case this let me use my onboard video for a theoretical 3 additional outputs, rather than the switching that lucid does, and use quicksync alongside my discrete card.
I'd add that with recent driver versions, having a monitor plugged in is NOT needed for quicksync use. However, the answer still holds true if you want to use the iGPU for output alongside a dGPU – Journeyman Geek – 2014-06-20T03:06:50.067