If your payment is stuck on this screen and it's been over 60 seconds, then it took the server too long to respond. This may happen on a large payment with a high number of charge lines added to it.
Don't worry! Your data was already sent and the server is processing it. Go ahead and refresh or just close the tab and reopen Lightning in another tab.
Allow a few minutes for the payment save to complete.
*We are working to correct this issue.