I just downloaded the newest version of Kontakt 6.3.1. Now whenever I close an instance of Kontakt in Cubase 10.5, it hangs Cubase, and I need to re-start Cubase.
This used to happen also in old Kontakt 5, but not in Kontakt 6 until now.
I know this doesn’t help, but no problem here with 6.2.2 on C10.5
Can you recall whether the problem existed with your previous version, and what that version was?