More info is needed to assist you.
Do you see other riders in game? If you don’t, it means you’re having Internet issues.
Are you crashing when you exit the game? If you crash, we can’t upload your data.
When you select Save from the End Ride menu, does it show Save + Strava on the icon? If it doesn’t, it means your Zwift and Strava accounts aren’t connected.
Does the activity show up on your Zwift Dashboard? If it doesn’t, it means it didn’t upload successfully, and there was a problem with the connection with your Internet connecting to our servers.
If none of those steps help, please submit a support ticket and one of our Zwift support colleagues will be happy to assist you further. Thanks!