Kerbal Space Program

It's still happening in 1.12

It's happened to me, but of course, when I tried to replicate it, I can't right now :-(

If you watch the vod of Terahadra on Twitch, you can see this:

https://www.twitch.tv/videos/1092767386, about 1:10 hour in, and watch for about 5 minutes

It isnt bug, it showed intrcept with mun after many many orbits later. He would have figured it out if he hovered mouse on intercept icon when creating maneuver node, it would have shown time for that intercept after maybe 10days. He should have checked ejection angle before making burn, it was totally Off.

Yeah, I'm not certain that specific example is a bug (though if jukkamuhonen is correct it's still a failure of the game to effectively communicate what's going on), but if you are observing these symptoms in gameplay, they could also be related to #25227 where the patched conics fails to report an encounter, which I can still reproduce in 1.12 (though it seems I can no longer update the version for that issue).

Not a bug.

The trajectory is predicted assuming your burn is a "instant kick", which is actually not. During a 30s burn in LKO, your craft travelled more than 70km and velocity changed more than 300m/s due to kerbin gravity. These will affect your trajectory.

Also in the video, your planned trajectory is just touching the very edge of mun's influence sphere (so the returning trajectory is not affected too much to hit the kerbin), so it's very likely a small error in burning will make you totally missed the mun. In that case, you should correct your trajectory ASAP, instead of time warp.