Ignore post, found the simple mistake: Used the wrong field. If anyone can delete this post please do.
I have a field called metric.time_delta which is stored as seconds. I would like to display this field as minutes, or "Human readable" called in the format section. I followed the instructions in this thread: Showing milliseconds as seconds which is exactly what I want to achieve (except seconds->minutes instead of millis->seconds).
However when I later do a simple aggregations as visualisations the formatting does not work. When i choose to sum on the field "time_delta" it only shows "a few seconds", but if I sum on the field "metric.time_delta" it does not format at all and shows the regular sum of seconds. Screenshots below: