Kontakt 5 hangs on close

I can open up and use instruments within Kontakt 5, but whenever I close the Kontakt instrument, eg using the [x] in top right, then the Kontakt instance goes white and hangs. Its seems to close OK after maybe 1 minute wait. Does not happen with Kontakt 6.

Windows 10, 64 bit, using the 64 bit version of Kontakt, Cubase 10

Any ideas?

Hi,

Make sure the plug-in is up to date, please.

Its Kontakt 5, version 5.8.1 - which I believe was the latest version of Kontakt 5.