I just received my STUDIO 68c and was able to download and install Studio One 5. When I try to add the LX61+ it isn't listed and the file download here http://support.nektartech.com/s.nl/ctype.KB/it.I/id.8576/KB.533/.f fails to install with a message saying that Studio One can't be found. I can manually add the LX61+ within the options box it and set it to all channels but none of the extra features/controls are working.
It all installed and worked perfectly with that download in Studio One 4 when I downloaded the Prime version to play with before my 68c arrived.
My system is a Dell XPS15 running Windows 10 Pro 64 bit and the LX61+ is connected via USB.
[EDIT] I found the MIDI Learn button as described by Gregor in his 'How to set up MIDI Keyboards and Controllers" video and the sliders on my LX61+ appear when I move them but the Play, Loop, & Record buttons (examples) don't appear when they are pressed.