rotation of eNvFlexShapeSphere

[What-a-stupid-username]

why do I need to set the rotation of eNvFlexShapeSphere to (1,1,1,0) to let it work correctly?

This is the simu of (1,1,1,0):

And, here is (0,0,0,1):

The result seems that the top of the cloth can no longer get closer to the sphere and remain vertical as supported by some ghost thing.
Why? The identity rotation should be (0,0,0,1), and for the sphere, the rotation should not change the simulation result.

Also, when I change to use sphere triangle mesh, the rotation parameters act correctly.