End user stuck on "initializing remote session"

End user stuck on "initializing remote session"

For some reason as of this week all remote support sessions, whether sent by emailed link or when the session ID is entered into the pre-installed app, are getting stuck on a popup that says either "initializing remote session" popup and do not progress any further, "Failed to join the remote session. Contact technician for further information". 

This started on Monday and we've not made any changes to our environment.