The problem was in my application and now I found it on same opengl demo from net. My app uses OpenTK and OpenTK.GlControl in C#. Pc: all works fine, Nvidia 1080 ti Laptop: Dell, inspiron 7505, win 10, Nvidia 940m + Intel UHD.
When I try to resize opengl window, either manually or from code, the content disappears, sometimes flickers back on different sizes, but in general no frame is visible. Nothing is rendered in code, only Clear is performed to see different color.
Is this a driver bug? Anyone had similar issues?
Apparently I was downvoted without explanation. Was that so obvious?
Laptop uses Intel GPU to draw to screen, although NVidia GPU is used for processing graphics. Therefore, drivers update for Intel GPU solved the problem.