That only worked for me if I have a buoy with an engine. I will test again though.
Edit: I just tried it, definitely doesn't work. Didn't work for me in 1.11 either. It even says "Buoy Waypoint #1" Whilst stubbornly not being on waypoint #1 anymore, which has correctly followed the body.
Buoys, same as mines, are bugged; don't waste time with them. the big drawback is that you cannot even remove them afterward, leaving the map a disaster as well.
Steve did not test/realize as in his campaign he uses missiles with buoys which it's a working feature from launch and as you have tested as well works just fine.
I am sure he does read all these reports though so either he is not interested in touching this aspect at the moment or simply he hasn't yet found out why they don't work considering all was fine in VB6, therefore possible to achieve.
I recommend you limiting your buoys to sensors on Jump points (but again soon you'll be having plenty with no possibility to replace/update) and 2 stages missiles/sensors.