Sending data message means that Restream is trying to connect the platform and if that message stays for too long, that means we are having issues with it.
Here are a few things you can try to solve this issue:
Please try reconnecting Facebook to Restream making sure you have all the necessary permissions to stream to Facebook.
Try removing your Facebook channel from the Restream dashboard. Make sure to clear all permissions by enabling this option:
If you remove your Facebook without this option, you need to manually remove Restream connections at these pages:
https://www.facebook.com/settings?tab=business_tools
https://www.facebook.com/settings?tab=applications
After you clear all Restream permissions and applications at your Facebook, try adding Facebook to Restream once again, granting all permissions as shown in this article.