On the attached figure, my rocket is on the SOI of Luna, with 2 trajectories represented, one wrt Luna, the other wrt Earth.
If I hover the trajectory wrt Luna, a + sign appears to create a maneuver node, but when I click, it does nothing. If I instead hover the trajectory wrt Earth and click, it creates the node.
Either do not show the + sign to create the node on the trajectory wrt Luna, or allow the player to create a node on trajectories other than Earth (i.e. fix this bug).