I have had the same issue after migrated to a new PC.
In my case, the invalid LNK files in QuickLoad were the root cause of the issue, as I copied lots of stuff from the old PC.
There are several threads in the NI forum, e.g. Solved - Kontakt 6 Crash in Cubase | NI Community Forum and the suggestion was to delete the whole Kontakt preference folder.
It will likely solve this issue but is a huge lobotomy surgery.
I didn’t want to lose the bunch of the shortcuts in QuickLoad, but the issue started to happen again once I copied over the QuickLoad contents from the backup. This is it! Eureka! The issue must be related to the QL LNK files. Most likely the invalid, missing targets.
There are handful of the tools out there to help identifying the invalid LNK files.
I used shman (ShortcutsMan - Shortcuts Manager for Windows).
Run it by
shman /folders "%LOCALAPPDATA%\Native Instruments\Kontakt"
Once it finishes gathering the information, from the Edit menu, click “Select broken Shortcuts”, then from the File menu, click “Delete Selected Shortcuts”.
In case you wanted to keep a record of those missing links, do File / Save Selected Items before deleting them.
Now you should have fixed the kompletely annoying workflow blocker, and saved the majority of the Kontakt settings without losing lots of quick loads you’ve collected over the years.
(well, if your freeze shares the same root cause as mine. fingers crossed