Thanks for following up. In fact, roll back isn't my strategy, expecting that sooner or later the update becomes inevitable. So I searched and found the Windows error reports pertaining to the subject. I contacted Cakewalk support for tech help, and attached those reports.
Let's see what happens next.

Have you reinstalled the sound card drivers? (Also the drivers of the onboard sound card)

Not yet, but if the soundcard drivers are affected by the update, there should be new files. I'll check by the soundcards update monitor.
But I think this is not much probable, since only 1 VSt-instrument is affected. For checking, I took a track which is really loaded with a lot of VSt-I and VSt-Fx.
But I shall check for updates for the soundcard.

I just upgraded my motherboard and thought I would do clean install of my daw to get fresh start. Windows media creation tool of course, made the creators update version. All seemed ok first but I noticed bad dropouts in a track I had not had before. The dropout was first noticed on a track with Zeta +2. Could not figure out the reason, tried all kinds of settings but no help. Then I found this thread. So I can confirm it too.

I have been using the old 1511 Win10 version until now with no problems. So In will have to restore my image of that again.

Very disappointed I the windows creator update for DAW. A whole night wasted installing it all yesterday.

Nut using sonar but Cubase. So same thing there.