When testing an animation, if I play the level (in viewport or standalone) when the Animation BP tab is Open (selected), I get duplicate debug messages as if there are 2 objects in the scene. The first image shows the result when the AnimationBP is NOT open and the second when the AnimationBP is open. That is the only difference between runs.
EDIT: This also impacts the animation debugging, as soon as you go into the AnimBP, the AnimGraph is stuck in the first state and I am unable to debug.
NB The message is just a simple bool and the actor name.
Version: 4.27.1-17735300+++UE4+Release-4.27