this is the proven complete procedure on Mac:

Spoiler: steps

KONTAKT LIBRARIES after 5.6.0:
You have to open the Kontakt 5.6.0 standalone app (or 5.6.5) and add the library in it. If the library doesn't appear on the left panel, don't worry about it. Just close the app.
Open this new Kontakt 6 version, and if you can't see that library there, then you have to do the following steps (in case there is a .nicnt file in the library's folder) but first close Kontakt, then:
1. check the SNPID number of the library, go to the folder of the library and open the .nicnt file (with TextEdit or any similar program), you will find a line like this:
<SNPID>P74</SNPID>
(in this case P74 was the ID code of Metropolis Ark 3)
2. go to your hard drive > Library > Application Support > Native Instruments > Service Center, and look for the .xml file with the name of that desired library, open it with TextEdit and you will see that the SNPID number there is 000 which indicates that Kontakt somehow hasn't been able to add it properly. Change that three zeros with the ID code you found in the .nicnt of that library, then save and close TextEdit. And you're ready to use the library in the new Kontakt.
During this process Kontakt app should not be opened!
If you encounter the problem where Kontakt prompts you after you try to load the instrument that "This instrument belongs to a library that is currently not installed", in this case delete the library's .xml file from:
your_hard_drive > Library > Application Support > Native Instruments > Service Center
And also delete the com.native-instruments.{library's name}.plist file from:
your_hard_drive > Library > Preferences
Then try to add the library again in Kontakt 5.6.0 and follow the SNPID workaround from above again.

 

So, I digged a bit deaper in this case.
There is an updated (v 1.4) library that has an installer for windows only, I had to extract the exe file and found not only .nkx/.nkc but an .nicnt file, too. When I tried to add it in Kontakt 5.6.0 it apparently went smooth, I could load the patches but right after I closed Kontakt, the prompt message appeared whether I want to add this library. As Kontakt was already closing, it didn't create the .xml file.
However, the library maintained showing up on the left panel of Kontakt (in both 5.6 and 6.x.x) and patches loaded just fine. Without any related .xml file in Service Center! If I copied the extracted .xml file from the installer (that has the name correctly West Africa.xml) and put in Service Center it also worked with no difference.
I think in the updater there is some redundancy, if it has the .nkx, would be no need for the .nicnt file, therefore Kontakt is struggling when trying to add it twice.

 

Possibly:

Native access was updated and used by you recently and the folder permissions were changed ,
this can also help if you notice an sc3.temp file automatically created on user desktop.

it's just that you as a user don't have the rights\permission to add the newly made .xml to Service Center Folder.

On a mac all you have to do is change Service Center folder permissions and add yourself as read and write owner.

on my mac i changed it mac HD>Library>Application Support>Native Instruments>service center

Then sc3.temp is never created on desktop, and the added library shows up on Kontakt 5 and Kontakt 6

hope it helps.

 

I've never had a problem installing libraries with 5.6.0 until CineBrass Horns of the Deep. Getting the "This instrument belongs to a library that is currently not installed" issue. I tried the steps @tzzsmk posted above (correcting the .xml with the proper SNPID, and then even deleting it along with the plist file and re-trying the install and editing the new .xml file again) but still nothing. Is there anything else to try? Any ideas, anyone?

EDIT: The library also won't work from Quickload and still pops up with the same error message.

 

Last edited: Dec 21, 2020