Date Mapping Format Not Working

Hello guys,

I have used a timestamp the comes from Logstash looking like this:
2016-09-30 02:45:22,533-0700

In mappings I have set it as:
"timestamp": {
"type": "date",
"format": "yyyy-MM-dd HH:mm:ss,SSSZ"

However in the alias/index, the timestamp appears a string type. I have a previous index in the alias with the timestamp set as a string, but I created a new index with the timestamp as a date type with the above format mentioned. My new index is working fine, but the new Date Format on the "timestamp" field does not seem to change?

Can you show us the mappings?

Can you also share your logstash config file along with ES mapping?