\uD83E\uDD14 Problem
When migrating with CMJ, the custom events added in the Notification scheme are not migrated.
\uD83C\uDF31 Solution
The custom event is not included in the snapshot if there are no actions added to it.
Please check if action(s) are added to the custom event in the Notification scheme.
Add at least one action to the custom event to include it in the snapshot.