Bulk from python doesn't parse datetime type

Hello, Elastic community!

I'm trying to load a bulk to Elasticsearch from a large dataset using a python script to parse. My data source file is made up of several columns with float type values and a last one with datetime format entries (yyyy-MM-ddTHH:mm:ss.SSS format). The mapping is successful, but the datetime values are mapping as "text" into the index. Why ES doesn't recognize this format as datetime? I've tried with different formats and the problem is the same.

PS: My goal is create an index pattern in Kibana to use Timelion for time series visualizations of this data with this datetime values. I use ES 6.7.

Then try mapping time field statically

It works, thank you!