I've noticed exactly the same problem in iOS Zoom. In fact as host my video feed is always a thumbnail, floating around - of no use to me. I am not shown on the gallery view - but am listed on the participants list.
What is worse is that swipe right to go to speaker view only shows the first person to join the meeting - it will never show the host (me) even if I am the only person speaking, so should be shown on speaker view.