Retrograde burn does not decrease orbital velocity
When loading this craft in my savefile, I am attempting to do a retrograde burn to form an orbit around Minmus. I have aligned the craft with the retrograde icon on my navball, but firing the engines does not decrease my orbital velocity, rather increasing it. If I flip my craft around to do a prograde burn instead, my orbital velocity still increases. This leads me to believe this is some kind of a physics bug.
In the savefile 'weird velocity bug.sfs', it looks like the nav-ball is set to use as its control point a docking part on the side of the rocket.
That docking port is pointing retrograde, but the rocket is not.
If I right-click on the command pod and select 'control from here' the nav-ball orientation changes, and then if I rotate the craft to the command pod is pointing retrograde, the rockets slow down the craft relative to Minmus, as expected.