Kibana Discover UI doesn't recognize newly added indexes in an Alias

Question

I create monthly indexes from Java Code (using Elastic HL Rest Client) and they have an alias name. So eg, the index names are of the format elk-gps-kafka-MMYYYY and the alias name is elk-gps-kafka-store I have created an index pattern for the alias in Management section of Kibana in august 2020. So if I search a data using _id field for a data present in July 2020 index, it shows on the discovery UI but if I search using an _id which is present in October 2020 index, it doesn't show on the discovery UI.

However I am able to retrieve this same record present in October 2020 index using _id through query on both index as well as alias.

GET /elk-gps-kafka-102020/_search/
{
        "query": { 
        "bool": {
         "filter": {
                "term": {
                   "_id": "GKDVQHUBntLICdSPemNC"
                }
            }
        }
    }
}

GET /elk-gps-kafka-store/_search/
{
        "query": { 
        "bool": {
         "filter": {
                "term": {
                   "_id": "GKDVQHUBntLICdSPemNC"
                }
            }
        }
    }
}

I'm Using Elastic 6.6 So the issue is basically index pattern doesn't recognize newly added indexes to the alias.

@Val, Running GET _cat/aliases/elk-gps-kafka-store, shows the data for elk-gps-kafka-102020 index and can query the _id from console but not from discovery UI.

elk-gps-kafka-store elk-gps-kafka-092020 - - -
elk-gps-kafka-store elk-gps-kafka-112020 - - -
elk-gps-kafka-store elk-gps-kafka-012019 - - -
elk-gps-kafka-store elk-gps-kafka-082020 - - -
elk-gps-kafka-store elk-gps-kafka-122020 - - -
elk-gps-kafka-store elk-gps-kafka-062020 - - -
elk-gps-kafka-store elk-gps-kafka-102020 - - -
elk-gps-kafka-store elk-gps-kafka-072020 - - -
elk-gps-kafka-store elk-gps-kafka-012020 - - -
elk-gps-kafka-store elk-gps-kafka-052020 - - -