Writing queries with Python doesn't correctly add tags/fields

I’m a bit confused why Influx is wanting to store my tag values as field values. I’m using the Python api and writing data with the following code for the very first write. This should set source and type as tags. Hoping someone can see something that I’m missing.

    measurement = "filter"
    current_filter_change = 0  # first time we are writing to DB
    # write record to DB
    filter_tags = {"source": "python_app", "type": "change"}
    filter_fields = {"current_filter_change": current_filter_change} 
    influxdb_write(measurement, filter_tags, filter_fields)

and then the following for all subsequent writes:

filter_tags = {"type": "reading", "source": "python_app"}
    filter_fields = {"adc": values[3], "voltage": voltage , "psi": psi, "pump1_rpm": current_pump1_rpm, 
"current_filter_change": current_filter_change}
     influxdb_write(measurement, filter_tags, filter_fields)

The function influxdb_write is just a wrapper for the proper format:

def influxdb_write(measurement, tags, fields):
    global client
    # Expecting measurement to be a name, tags to be a json object, and fields to be a json object.
    # We will not pass time and let the database handle that.
    # >>> example json_body = [
    #     {
    #         "measurement": "cpu_load_short",
    #         "tags": {
    #             "host": "server01",
    #             "region": "us-west"
    #         },
    #         "time": "2009-11-10T23:00:00Z",
    #         "fields": {
    #             "value": 0.64
    #         }
    #     }
    # ]
    # >>> client.write_points(json_body, time_precision='s')
    json_body = [
        {
            "measurement": measurement,
            "tags": tags,
            "fields": fields
        }
    ]

    print(json_body)
    result = client.write_points(json_body,'s')
    if result == False:
        log("ERROR!!! Write result for {0} is {1}".format(measurement,result))
        send_sms_alert("InfluxDB", "Cannot reach server.")

The output of the print statement looks good as well…

[{'fields': {'current_filter_change': 0}, 'tags': {'source': 'python_app', 'type': 'change'}, 'measurement': 'filter'}]
[{'fields': {'current_filter_change': 0, 'psi': 2.53, 'pump1_rpm': 1400, 'adc': 4810, 'voltage': 0.6}, 'tags': {'source': 'python_app', 'type': 'reading'}, 'measurement': 'filter'}]

However, running a select * from filter in InfluxCLI I see:

> select * from filter order by desc
name: filter
time                 adc  current_filter_change psi  pump1_rpm source source_1   type type_1  voltage
----                 ---  --------------------- ---  --------- ------ --------   ---- ------  -------
2018-06-15T05:31:01Z      0                                           python_app      change
2018-06-15T05:29:52Z 4806 0                     2.52 1400             python_app      reading 0.6

I’m never writing the source and type as field values, but Influx is storing them as such.

show field keys has the following entries:

name: filter
fieldKey              fieldType
--------              ---------
adc                   integer
current_filter_change integer
psi                   float
pump1_rpm             integer
source                string
type                  string
voltage               float

as does show tag keys:

name: filter
tagKey
------
source
type

Please help me understand why Influx would create the source and type tags, but never store any data in them as I’m expecting.