I am a new sign up user, keep running into this issue: error initializing the dashboard, please try again , is there anyone who can help? 
I get this issue sometimes too.. If feels like the authenticate session has gone stale. My manual work around is to close the tab. Go to the retell website retellai.com and click login at the top right to start the auth process again.
This works for me, crappy workaround I know but at least keeps you moving.
I see someone has raised this wth Retell support, so hopefully a permanent fix is coming.
Russell