Whiteboard - Not being able to see information being added

I've recently tried to use the whiteboard in group sessions.  Have set up the whiteboard with several pages and headings in advance - all visible and I've been able to add info to the boards.  When participants have started to collaborate and add info to the boards, I lose all visibility of what was previously on the board and what's being added.  This is limiting me using the whiteboard as I can see nothing to facilitate discussions.  When I save/export the boards I can see the information.  I'm using Zoom Version 5.13.11 (16405).  Any ideas how to fix this?  Thanks