This is really strange. Here using Kontakt 5.6.1 R2R. I load a patch and after a short time (20 seconds, 60 seconds, etc.) the volume slider of Kontakt drops to almost 0. I return to adjust it and it happens again after a short time. Interestingly, this happens both in the standalone as in plugin and in all DAWs (Reaper, Live, Studio One ....) except in FL Studio!!. No matter what patch load. It happens with all the libraries.
I'm sure that it has to do with Kontakt's license protection system, even though my computer has no network.
I tried to install the "no install" version, but the problem continues. The same as if I completely uninstall kontakt and reinstall it.
Has it happened to someone else?

 

I had a similar issue but not copy protection related and not in stand alone, although depending on your midi hardware and the way it's setup (is CC7 used) it could cause the problem.
In samplitude cc7 were sent to kontakt (I think it was the faders, who can do that or send volume info to tracks) which then would lower the volume of the instrument who was monitoring midi at this point, despite the fact that it wasn't what I wanted (lower the volume of the track, in the mixer). Constant changes of volume of kontakt instruments, I couldn't understand why. Then I changed the option in sam to not send cc7 through moves of the mixer volume faders, it solved the problem.
Another way to stop that behavior, is to go in the options of the instrument you are working (not kontakt option), "instrument option", "controller" and you uncheck "accept standard controllers for volume and pan".
If that's the problem, it should fix it.

 

I have disconnected the MIDI controller and problem solved.
Uncheck "accept standard controllers for volume and pan" in instruments optinos also works.
Thank you very much.

 

Then if you know how you should unassigned cc7 from your midi controller, this way it won't happen again....And more important you will be able to keep using your controller....

 

You are right. However, I think just stuck some slider or button. The same thing happened to the modulation wheel, and the sound came sporadically out of tune. The modulation wheel is now disabled. Problem solved. Thanks again.