Why can't I switch from the Instant Join app to the desktop app?

If you were launched into session using the Instant Join app, then that means you joined Webcast or Recorded webinar, or are running an operating system that is not compatible with the desktop app, or had issues with the installation process for the desktop app.

Don't worry though, that's what the Instant Join app is for – to ensure that all attendees can get into session, regardless of their operating system!