Auto delete index on the basis of index size

I Want to delete two different production index if it exceeds 50GB size.
I tried to use ILM policy on the basis of index size, I tried rollover condition with hot phase max_size 50GB and then delete phase after 1 hour. But its not working.

PUT _ilm/policy/1-day-delete-policy
{
  "policy": {
    "phases": {
      "hot": {
        "min_age": "0ms",
        "actions": {
          "rollover": {
            "max_size": "50gb"
          },
          "set_priority": {
            "priority": 100
          }
        }
},
 "delete": {
        "min_age": "1h",
        "actions": {
        "delete": {
         "delete_searchable_snapshot": true
      }
    }
  }
}
}
}

Please suggest.

Can you please do an ILM explain on the index?