This is often happening to me, here the example:
As all dinos do, my Einasuco moves a bit when battleing, so here you can see her head up:
But before receiving the Great Stunning Strike, I move first with Adrenaline Pulse and my Einasuco suddenly stops to move, so I already know that Stegoceratopo will stun me:
And here when the Stun warning is shown is red (it is the second stunning move, but just to explain well, as I am not able to make bursts of screenshot XD ):
Not a big issue and it is not a priority thing that needs to be fixed asap, but honestly it takes out a little bit of fun seeing that you already know the results of the RNG before the attack is done.