We do apologize for the inconvenience! We’ve had delays on uploads to Garmin and are working to improve that delivery speed and will be reprocessing those activities. So any activities over the past few days that have not yet been uploaded will not be lost and will eventually be processed. All new activities should be uploaded without issue.
We’ve had many reports of users being unable to upload their rides to Garmin. It’s a server issue that we are currently investigating in attempts to fix. The rides/runs not saving can be sporadic, with you sometimes successfully uploading.
You can upload your rides/runs manually by using the steps in this guide: https://support.zwift.com/en_us/can-i-upload-my-.fit-fileactivity-to-a-third-party-site-BkWegRkWSm
We will update this thread as soon as we receive new information. Thank you for your patience!