I am running Zoom Linux version 5.8.0 on Ubuntu 18.04.
When I start Zoom I am often getting a broken GUI: The upcoming meetings / calendar widget is missing on the home window and the chat window only shows the participants list on a white background, but no chat. I often have to restart Zoom several times before I am getting a proper GUI.
This bug appeared with version 5.8.0. I completely reinstalled Zoom (including deleting the user data), but that did not fix the problem.