Secondary Hand Slot Glitches in Minecraft Mac 1.10 pre-1

When I go to the survival inventory section of my creative mode GUI, the second hand/secondary item slot glitches and appears black and corrupted. But for some reason, when i was dragging an item or when my cursor moved over it, it seemed to appear fine.

I hope all of you lovely people on the support team could fix that before the official release of Minecraft 1.10