Mun Encounter disappearing upon maneuver node creation

[Wizard Kerbal]

I forgot my password to the bug report things, so if someone could report this it would be lovely.

I just finished a burn to get a munar encounter, and wish to fine tune it. When I set up a node, my path continues to show a munar encounter, but the maneuver node's path shows my orbit if the mun just disappeared. 
Upon Munar SOI entry, it shows my path in blue, then a purple path going into the bottom of the planet.

This glitch really ruins the fun of the game, and it's the reason for all of my rage quits.

I have no idea what causes this or why it happens, it just happens.