iOS Picture in Picture - how to select screen share?

I’m using Zoom on iOS. If my colleague shares their screen, I see both their camera feed and their screen share. 

If I minimise Zoom, I see their camera feed Picture in Picture. But I want to be able to see their screen. 

There doesn’t appear to be away to select screen share as the PiP feed. Even if they turn off their camera, that just results in a black PiP, which is a bit daft. 

Anyone got any ideas?