The issue is now resolved and we are actively monitoring the performance. There was no data loss, but the delivery of webhook payloads was delayed. Note that attachment URLs in webhooks payloads were missing since 5:00 AM Thursday, Pacific Time (PT). They are also operational now.
Posted Dec 21, 2018 - 11:04 UTC
Update
We are continuing to work on a fix for this issue.
Posted Dec 21, 2018 - 10:59 UTC
Identified
Webhooks are non operational since 1:56 pm Thursday, Pacific Time (PT). Currently we are fixing the issue. ETA for fix is 30 minutes.