Very odd Nanokontrol 2 behaviour since updating to Catalina

[nano_nano]

I love my Nanokontrol 2. I use(d) it exclusively as a cc controller, within Logic Pro X for Kontakt libraries and the VSL Synchron player, plus customising other libraries. I do not use it as a general DAW control surface (ie: transport, etc).

Under Mojave it worked perfectly, but since upgrading to Catalina it has exhibited some very odd anomalies. Namely: certain sliders and pots mostly no longer work, even if I use MIDI learn, and in Spitfires Audio's Kontakt libraries, the sliders/pots cease to work, except for cc 11. It's inexplicable. I've tried assigning certain sliders/pots to control a couple of Kontakt libraries, but they simply fail to operate.

It is a completely random situation, but it's always the same pots and sliders at fault, if this makes sense.So, random, as in: no apparent underlying pattern to the same unresponsive pots and sliders.

I booted up my iMac from a Mojave backup and everything works, 100%,as I expected.I found a good website site from someone, giving instructions on how to get things working in Catalina. Initially, it seems to be OK, but I noticed, by accident, that some controls were not making the cc's operate at all. That's when I discovered this weird behaviour.

I have uninstalled the Korg stuff. Even stopped using the Korg driver, but nothing works. Incredibly frustrating. Can anyone shed any light on why this might be happening, please?

I have some screenshots available, if interested.

Many thanks.