I've noticed it happens to every test I do. I'll send a test project with "BoneFollower Issues" as Subject.
Basically, whenever I do -1 on the Scale in Spine (-1, 1), The Bone Follower in Unity gets confused and Flips upside down. This is really bad for stuff like shields (that go behind the player facing the other way), coins and a lot of other stuff.
Edit: Seem to be the "Follow Bone Rotation" under the Bone Follower that does a 180 on the z-rotation when it goes below 0? I can't solve this by unticking it, because:
skeletonAnimation.Skeleton.FlipX = true; //player flip
Above code on the SkeletonAnimation results in the SkeletonUtility to Scale (-1, 1, 1). But the BoneBollower objects results in Scale (1, -1, 1). Which means every time the player/skeletonAnimation flip, the bone-following-object will still be upside down without the "Follow Bone Rotation" ticked.