inaccurate maneuver nodes

[Waxing_Kibbous]

This has been happening pretty consistently- I do my burn from Kerbin to make the initial Minmus intercept, then I make an adjustment maneuver a few hours out. When I adjust both anti/normal and retro/prograde the blue target ends up centered on the normal, and the burn consequently only adjusts the normal, leaving me to do a separate retro/prograde burn after. Minmus seems flaky in general, one time I had a PE of about 25,000m, set up the node to orbit, warped to the node, and crashed into Minmus. Another time my intercept line just went away, leaving me to point directly at Minmus visually and burn to get it back.