[WATCHER] Failed to Transform payload - Keyword field

[Rossana (Raquel Acero)]

Hi,

I am trying to configure a Watcher of a machine learning job.
The ML job is a population job that works with keyword fields.

A cause of using the keyword field, watcher gives me this error:

This is the search of the watcher:

This is the original payload all good till here:

BUT
Tranform payload error:

I cannot access to fields keyword!!! What can I do?