Expert seeing "Oops, the connection timed out..." invite error

If you see this message: 
Oops the connection timed out. If your customer did not receive the invitation, click Invite to retry. 

That means: 
The invitation system waited 20 seconds but could not confirm that the invitation was successfully sent to your customer. 

What to do:
Please check if your customer received the invitation. If not, click the Invite button to send a new invitation. Alternatively, you can use the "Link & Code" invite method to send an invitation to your customer using a communication method other an SMS messaging.