MoviePlayer on Windows works differently to MAC

I created the same small app on both Windows and MAC versions of Xojo
Just a MoviePlayer loading a movie (20 secs) then playing it, then a MsgBox saying “Movie has finished” when the movie ends.

I added a movie called TwentySecondTimer to my project
I added MoviePlayer1 to Window1 of my project (any player type Quicktime, Preferred Player or Windows Media Player)

I added the following to the event:
MoviePlayer1.Movie = TwentySecondTimer

I added the following to the MoviePlayer1.stop event
MsgBox(“Movie has finished”)

On Windows 10 the MoviePlayer.Stop event is executed immediately the app is run showing the msgbox - on pressing the OK button the movie runs and again displays the msgbox
On MAC OS 10.12 the MoviePlayer loads the movie and displays the msgbox at the end of the movie

Does the MoviePlayer1.stop event take presidence over the event on Windows 10?

It seems like (in Windows 10) the act of telling the movieplayer the movie to load, fires the movieplayers stop event?
But not on the MAC