Multiselect with optgroup and keepRenderingSort doesn't work

Multiselect with optgroup and keepRenderingSort doesn't work

Good day everyone,

I am setting up a Multiselect withoptgroup  and then I have:

keepRenderingSort: true

But it doesn't work, the order of the items is altered and the whole optgroup moves to the bottom of the list when I move an item from the right dropdownbox to the left one.

https://crlcu.github.io/multiselect/

Any advise?

https://crlcu.github.io/multiselect/#sort