I have this problem in Rhino 9 WIP where the layers and properties panel or basically the whole right sidebar is unresponsive. Toggling the sidebar allows me to get into a panel. I could not figure out yet what exactly triggers this.
It happened again. Maybe after caching some model objects. Not sure.
This is my current layer panel:
When I open another app, for example the browser… it looks normal but I cannot click any layer.