Ship not maintaining heading when focused on another ship

[ThirdHorseman]

I am having an issue where ships that are not currently the active vessel are not maintaining heading with SAS.

https://imgur.com/a/pZWRu

The ship that has my Kerbal is in atmo on Kerbin and detaches a probe.  I switch focus to this probe, set SAS and set heading to be retrograde.  This works great and the probe maintains a retrograde direction as it decends.

I switch focus back to the other ship and watch as the probe descends and I can see it start to tumble.  I switch back to the probe and it has indeed started tumbling around, but now that it is the active vessel it regains a retrograde heading and maintains it as long as it is the active vessel.  At any time if I switch back to the other ship the heading is again lost.

Is this a stock bug?  I have several mods installed but nothing that I think could mess up heading and SAS controls.  Has anyone else seen this?