This is not a bug: it's common practice to use a rectangular, non-animated object for the Platform behavior, and position the animated player on top, to avoid exactly this kind of problem.
See how to make a platform game:
he Platform behavior can take care of the complexities of platform movement for us. However, there's one important tip for using it: the behavior should be applied to an invisible rectangle object, and the player positioned on top. The Platform behavior works much better if the object with the behavior doesn't animate, since changing animation frame can leave the object partly sticking in to a wall which can confuse the Platform behavior. Also, it avoids silly collision situations like your player hanging off a ledge by their nose or something they're holding.