{{.Tags}} is empty when querying InfluxDB populated by Collectd

I'm using a setup where Collectd is pushing metrics into InfluxDB with alerts via Kapacitor and Chronograf on top. Influxdb is version 1.2 and Kapacitor and Chronograf is version 1.3. I can successfully create alerts via TICK files or via Chronograf and they get triggered appropriately, however when I try to format my message I don't seem to be able to get access to the relevant tag_keys and tag_values via the {{.Tags}} map. I use the following message in Chronograf

` {{ index .Tags "host" }}:{{ .Name }}:{{ index .Tags "type_instance" }} is {{.Level}} value: {{ index .Fields "value" }} @ {{.Time}} {{.Tags}}`

and receive the following message on Slack as a result:

`:cpu_value: is CRITICAL value: 47.12757803790413 @ 2017-07-28 13:21:00 +0000 UTC map[]`

The map of tags appears empty.

This is the TICK script that gets generated by Chronograf:

`var db = 'metrics'

var rp = 'default'

var measurement = 'cpu_value'

var groupBy = []

var whereFilter = lambda: ("host" == 'salt-master') AND ("type_instance" == 'idle')

var period = 10s

var every = 30s

var name = 'Salt Master CPU'

var idVar = name + ':{{.Group}}'

var message = ' {{ index .Tags "host" }}:{{ .Name }}:{{ index .Tags "type_instance" }} is {{.Level}} value: {{ index .Fields "value" }} @ {{.Time}} {{.Tags}}'

var idTag = 'alertID'

var levelTag = 'level'

var messageField = 'message'

var durationField = 'duration'

var outputDB = 'chronograf'

var outputRP = 'autogen'

var outputMeasurement = 'alerts'

var triggerType = 'threshold'

var crit = 70

var data = stream
|from()
.database(db)
.retentionPolicy(rp)
.measurement(measurement)
.groupBy(groupBy)
.where(whereFilter)
|window()
.period(period)
.every(every)
.align()
|mean('value')
.as('value')

var trigger = data
|alert()
.crit(lambda: "value" < crit)
.stateChangesOnly()
.message(message)
.id(idVar)
.idTag(idTag)
.levelTag(levelTag)
.messageField(messageField)
.durationField(durationField)
.slack()
.channel('#embassyalerts')

trigger
|influxDBOut()
.create()
.database(outputDB)
.retentionPolicy(outputRP)
.measurement(outputMeasurement)
.tag('alertName', name)
.tag('triggerType', triggerType)

trigger
|httpOut('output')`

Reproduce the alert using the supplied Collectd/InfluxDB setup and generated TICK script, starting with the alert() message template and the stream's groupBy, whereFilter, window, and mean stages. Trace where the tags disappear; done means explaining the empty .Tags map and identifying the required behavior for this alert path.

Written by the indexing model from the issue text.