As said by Matthew, this is related to the release. The Random feature was Merged shortly after this version that is in the cloud. There is still no forecast of cloud version upgrade.
If the issue is another do this:
Run this to check if there is any dataset anyway.
{
q(func: has(name), first: 5) {
name
uid
dgraph.type
}
}
If you see results and there is node with dgraph.type = “Person”.