I've seen many people having this same issue but I've not found an answer that has resolved my problem. I know this was a bug in ES 7.5 but I'm using ES 6.8.
I've got logs with dates/times in the format "09/23 14:16:16". I prepend the current year to that to get "2020/09/23 14:16:16". After I index the document, I can perform a search in the Kibana console and verify the date is correct. But, any time I search with 'Discovery' or create a visualization in Kibana, the 'DateTime' field is off by 4hrs. I've went into the 'Advanced Settings' in Kibana and tried both the default 'Browser' setting for the timezone and the actual timezone I'm in but neither has any affect.
Below, is my mapping for the field:
DateTime: {type: "date", "format": "yyyy/MM/dd HH:mm:ss.SSS"}
Also, how does daylight-savings work with this?