Kapacitor values out by one?

Hi,

I am new to kapacitor and using it to calculate percentages and totals using a batch function. This is being run side by side with the previous reporting solution.

I have run into a strange issue though where the values that kapacitor collects from InfluxDB and the values that return from the InfluxDB CLI. The values in kapacitor are one out (+1 on one field and -1 on the another).

I have checked the source data and the values stored in InfluxDB are correct, which leaves kapacitor.

Tick script (some data sensitive data removed):

var clearbags = batch
    |query('''
        SELECT last(bag_counts)
        FROM "somedb"."autogen".conveyor
        WHERE "conveyor" = 'name'
        ''')
            .period(24h)
            .every(24h)
            .groupBy(time(1m))
            .fill('previous')

// Get reject route counts
var rejectbags = batch
    |query('''
        SELECT last(bag_counts)
        FROM "somedb"."autogen".conveyor
        WHERE "conveyor" = 'name'
        ''')
            .period(24h)
            .every(24h)
            .groupBy(time(1m))
            .fill('previous')

// Join to get a total number of bags
clearbags
    |join(rejectbags)
        .as('clearbags', 'rejectbags')
    |where(lambda: "clearbags.last" > 0 OR "rejectbags.last" > 0)
    |log()
    |eval(lambda: "rejectbags.last" / ("clearbags.last" + "rejectbags.last"))
        .as('pct_to_level3')
    |log()
    |influxDBOut()
        .database('somedb')
        .retentionPolicy('autogen')
        .measurement('line')
        .tag('plc','none')
        .tag('area','sss')
        .tag('terminal','1')
        .tag('conveyor','some')