ILM my index is not doing rollover properly

Below is my ILM policy

{
  "policy": {
    "phases": {
      "hot": {
        "min_age": "0ms",
        "actions": {
          "rollover": {
            "max_age": "30d",
            "max_size": "50gb"
          },
          "set_priority": {
            "priority": 100
          }
        }
      },
      "warm": {
        "actions": {
          "forcemerge": {
            "max_num_segments": 1
          },
          "set_priority": {
            "priority": 50
          },
          "shrink": {
            "number_of_shards": 1
          }
        }
      },
      "delete": {
        "min_age": "330d",
        "actions": {
          "delete": {}
        }
      }
    }
  }
}

I assigned it the index template successfully. But even though the index exceeds it's size to more than 50 GB but it is still not rolling over to the the warm phase. Instead presisting in the same state. Can somone tell me what's wrong here.

The size limit refers to the size of the primary shards and since you have a replica configured you have not yet reached it.

This size here 59 GB is equal to primary shards size + replica size?

How can I see the primary shards size @Christian_Dahlqvist ?

You can use the _cat/shards API but as you have one replica it should be close half the total size reported in the UI.