So I got my NUC8i7 yesterday and configured it using OC6.0, will update to 6.1 later. I have the USBC ports working properly and sleep works as well, I didn't add the Beta Wireless kexts discussed on this page because sleep is more important to me that connectivity or working wireless at the moment.
I attached my updated EFI folder only so you can compare the contents of it to yours, if you look at them side by side you should begin to get some answers as to what works and what doesn't. Compare the two config.plists side by side as well, it’s possibly the most important aspect of any OC configuration.
I have renamed some of the SSDT files for ease of configuration in the config.plist so keep that in mind. If you think I'm missing or have an extra file you don't have in ACPI/Add that could be the real reason. What I found is that without adding the SSDT for USBC the Thunderbolt/ USBC ports do not show up at. Not in Hackintool or IORegistryExplorer.App, they aren't enabled without it.
A little history on that SSDT Rehabman, who started this excellent thread, created it back when we used DDST and SSDTs to configure some of the hackintosh functions kexts or drivers didn't address. Things have changed since then but that file remains necessary to enable the USBC ports. I believe there are other similar SSDTs that have been in development that allow hot plugging of Thunderbolt devices but I have not tried them on the NUC8s. I think they may work in the same way and may enable the USBC ports as well. The NUC10i7 configuration utilizes one is why I mention it and USBC works.
Once I added the SSDT-USBC.aml file to EFI/OC/ACPI folder (see my EFI attached) and enabled loading it via the config.plist it changed everything. Following the guide for USB Configuration I sent you earlier I then added USBInjectAll.kext, enabled it, and set the Kernel Quirk for "XhciPortLimit" as "/true" the USBC ports showed after rebooting. From there I used Hackintool to decide which ports to enable and created the USBPorts.kext, also attached in my EFI folder. Once that was created and added to the kexts folder/ enabled in the config.plist I then turned off USBInjectAll.kext leaving XhciPortLimit" as "/true. You can also leave USBInjectAll.kext enabled and turn off XhciPortLimit, its basically the same thing IMO.
Hope that helps explain a little more
Thunderbolt/USBC ports showing in Hackintool
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My Final USB port Selection before Creation OF the USBPorts.kext
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