Hello,
i'm the author of ItemPhysics, lately i got a report of spinning items inside the Obelisk with ItemPhysic installed(CreativeMD/ItemPhysic#15).

There is a rather easy way to fix it:

You only have to add this line

RenderItem.renderInFrame = true;

at the beginning of

private void renderItemStack(T te, World world, double x, double y, double z, float tick)

inside ObeliskSpecialRenderer
and this line at the end of the method

RenderItem.renderInFrame = false;

This will prevent ItemPhysic from spinning the item instead it will be handled as an item inside a frame.

It's not quite that easy. renderInFrame also disables vanilla rotation, so we'll have to do that ourselves.

Yes, i forgot that part :D
Never saw an Obelisk therefore i thought the item would stand still.