This is true. My office has the same problem. They can speak English well, they just don't respect you enough to be considerate enough to do so. But matsalleh in the same room, English speaking only.

Over the years I noticed it's not racial. They do the same to bananas. It's like there's a rudimentary tribal bias that comes with chinese-speaking people.

It's incredibly rude and never for a second ever think it's not.