As I mentioned I had tried that workaround and that did not work for me. Thank you for your input though.
Huion have just emailed me the following (verbatim) if it is any use to anyone:
"To be honest, even Wacom also cannot achieve the pen pressure sensitivity without slecting "windows ink" in the PS CC2017 in Windows10.If you want to achive pen pressure without selecting "windows ink" ,it is impossible to achieve it and it violate the related standard protocol. Windows ink is Microsoft's new standard protocol, the version above PS CC uses the windows ink standard protocol ; Win Tab is the old standard protocol and the version below PS CC uses it.
Compared to famouse brands Wacom, we still have much to learn and we are yruing our hard to overcome this issue, please kindly undertsand it.
Many thanks for your kind consideration on this matter."
This fix worked for me and my Cintiq Pro 16.
CC 2018 finally feels responsive again!
Am I loosing any functionality by turning off the windows ink?
Btw, @squiddie , verify if your txt file is not named "PSUSerConfig.txt.txt"
my file had a 2x "txt" typed and thats why the fix was not happening.
Oh, I see. This way the other applications will keep full features.