It is a security issue. However you have likely given cubase privilege to so.
On a mac this is done with settings->security&privacy->accessibility.
Cubase ask for access, and for most users it is valid for cubase to have access to audio inputs.
If you were someone who needs 24/7 remote access to 36TB of spinning disk, nightly backups of over 8TB of data, and access to sophisticated home automation wherever you, then keeping your computer running all the time is a necessity.
You need to save energy? Turn your computer off.
Screensavers and power safe modes make most audio hardware instable, and this is crashing the software sometimes.
Nearly all audio and video software disables the power safe modes and the screen safer.
2) If I add multiple Virtual Instrument track and load Komplete Kontrol on each of these tracks, then I can use the S88 to browse and select virtual instruments. Works fine. Also the DAW controls (play, stop, etc) work.
3) When I close and re-open the cubase project then for some reason the VI tracks are not recognized anymore by the S88. That is, I don't see the instrument on the display of the S88. It just shows the general midi screen (but I can still play the instrument from the S88)
Thanks for the replies. The solution turned out to be simple (of course ?). I unstilled the driver and and the komplete kontrol software from Settings --> Apps. Next I reinstalled, and now everything seems to work.
Confirm that you have set up Cubase so that the S88 is an input MIDI device [Komplete Kontrol -1 driver] (for playing notes & track/instrument focus) and a separate setup as a Control Surface [Komplete Kontrol DAW-1 driver] and see if that helps.
I just ran a test here (using an M32) with the same OS/Cubase/KK versions and everything works as expected, The fact the OP is having issue with the KK Daw driver makes me think that is the culprit...
I ask this because using Cubase's Quick Controls (which are based on the first 8 parameters of the VSTi) on the hardware, one knob/fader of the eight available will be lost, making knob/fader number 1 unused. Bringing the available controls to 7.
Alternative (perhaps hardly feasible): we can ask Steinberg if he gives us the possibility to change the numbers of the 8 Slots (not the parameters) to be associated with the Quick Controls. Example: instead of 1-8 we could choose 2-9 (or other as desired), so Slot 1 remains for the NIKBxx parameter.