Exploring of cross-account encrypted snapshot may fail with
error: Reason: Encrypted snapshots with EBS default key cannot
be shared (OperationNotPermitted)
If you receive the error above, please note that exploring a
cross-account snapshot with default CMK is not supported by AWS.
Creating another CMK on each account will not suffice. You will
need to change volume's encryption key to the non-default one.
Please follow the below document to migrate data between
encrypted and non encrypted volumes