MQTT parsing collectd data

I’m receiving collectd data via collectd-mod-mqtt plugin (openwrt).
it sends on the data in format timestamp:value\x00
that is a zero at the end.

I was able to parse it using CSV data format, as string, and then I can use processors.regex to remove the last \x00

The problem is that I can’t format it from string to integer with processors.converter

[[processors.converter]]
  [[processors.converter.fields]]
    integer = ["value"]

It has no effect.

I managed to fix it by using processors.string instead. That way all worked as expected.