Ye this is what came to my mind. For this problem the viscous force should in theory be pointing in the positive x direction. Looking at the forces plot it is indeed positive, but wall shear stress contours are saying otherwise.
So in theory, from the moving body’s perspective, viscous forces should be acting in the positive X. From the flowing air’s standpoint, viscous forces are in the opposite direction, due to third newton’s law.
But this is just a possibility, only by examining the code it would be possible to know exactly what is going on, I suppose.
PS: do you have any older simulations with plotted wall shear stress that you could verify this theory?