Issue: Distance of closest approach constantly changes during orbit.
Notes: If you have one vessel focused, the closest approach distance will constantly increase. If you focus the other, the distance will constantly decrease. If you time warp, the distance will freeze.
Long description: When trying to do a Munar Orbit Rendezvous on a mission. I had to make multiple attempts to get a closest approach lined up since everytime I would get near, my vessels would all of a sudden miss each other by thousands of kilometers. Playing around with this, I set up a bunch of maneuver nodes and got a closest approach of 250m. I took some screencaps and then noted that my approach distaance was now about 2500m.