I tried this out for myself (alas with Prometheus).
So without the transformation, I’m getting a time series with two fields (and many labels).
With the Labels to fields transformation applied, all the labels have been extracted to individual fields, e.g. cpu, instance, job, and mode.
By setting the Value field name, I can essentially group by the values of the selected label. Note that the Value field has been replaced with idle, iowait, and irq which all are values in the mode field.
If the Value field name box doesn’t list any labels, I suspect that it has something to do with the format that InfluxDB returns. I’ll get back to you once I’ve found a InfluxDB setup to test this one.