Let me try again, as I'm sure x264 was overruling min-keyint with content with very short scene changes.
.....
Sorry, you are correct- it works fine with min-keyint, but it's not end of my problem.
I also need some forced ones and when I do it with ffmepg than min-keyint is not working around this forced IDR places (which is expected I think).
Maybe I never run a test with min-keyint, but without forced frames
I have also found new option in ffmpeg: forced-idr=1, which forces forced frames to be for IDR (e.g. not just I). I think I need to do more tests.