Skippable "Get the latest update"

Sure:

As I said, after the skip, all things work as they are supposed to.
I did reinstall all the main modules (except for the instrument libraries) and the Native Access itself. System settings are ok, both under disk access permissions and app accessibility rights. I’m running Sequoia 15.4.1, M1 MacBook.

Same deal when I’m connected to my Windows PC.

Firmware updater says I’m all set (tried it on both systems).

I’m sorry to say it has only gotten worse after the steps you suggested. Now the screen pops up in every DAW before loading, both in Win and Mac.
Also, new screens in DAWs:

this one after pressing the BROWSER button (not responding to any of the highlighted buttons/knobs), and:

this one after hitting PLUG-IN. But, all the time, the keyboard plays the patches that have been set up with a mouse. And piano keys respond as they should.

In Komplete Kontrol/Kontact standalone, all is well and dandy.

I’m at a loss here, perhaps the firmware update went wrong? Is there a way to reset the keyboard to factory settings and reapply the firmware patch?

I appreciate your efforts, but it seems that the problem is not with my Mac, but with the hardware, as the keyboard displays those errors and quirks also in Windows. Here are some specific examples:

1. Logic Pro /Mac/

I manually load KK as a plugin, browser shows in a window, but keyboard screen remains in Default Midi state. I can load anything with a mouse from a KK window, but with no preview sound. When I press a keyboard key on the kk mk3, the selected preview sound plays and then all previews are heard, but only when selected with a mouse (keyboard screen is now in mixer state - DAW lights up). The patch shows as normal in a plugin window. Keyboard is playable now, both plugin window and in Logic, but the screen remains in mixer mode. I can switch tracks with the big knob (left/right), obviously, and transport controls and such work as they should, but I never see the instrument on the keyboard screen. KK plugin window does not update with track switches, I have to close it and reopen.

2. Ableton /Windows/

Keyboard screen says get the latest update. Did try on Windows, too, updater says I’m on the latest firmware. Skip. Daw lets me manually load Komplete Kontrol as a plugin. Again, same deal, browse only in the plugin window, but at least the preview sound works right away. I try Kontakt 8, it works! Keyboard screen behaves as it should. BROWSER, PLUG-IN light up. I select a patch and all works as it should. Here it gets interesting: I add another track, say Kontakt 8 again, all is fine. But when I switch to the previous one, bam, I’m back in default midi, Switch back, same thing. Hmm, let’s try Komplete Kontrol again, wow, this time it works! LEDs show different regions, I can browse, filter, all dandy… until I switch tracks, that is :/

Maschine 3 /Windows/

I can add patches manually, they show under PLUG-IN, even after I switch tracks back and forth. But BROWSER says no results found (see photo in my previous post), and all the knobs and switches around the screen are non-responsive, even if lit up. Best deal thus far, although I miss transport features and stuff.

I won’t trouble us both with Bitwig /Win/, Maschine 3 /Mac/, and a couple of assorted trial version DAWs, as there are no consistencies between the lot of them.

I tried all configurations, different USB cables and ports, etc. Nothing helps. Shame, really, as I like the keybed itself and I have my trusty Maschine Mk3 to make up for some of the missing features.