I'm attempting to add a new static field on an existing index, and having struggles getting data back in the preview to verify syntax.
I've confirmed that both fields are registered as "date" type in the index.
Here's the config I'm trying to use in the Scripted Field designer:
Format: default (number)
return doc['end_time'].value - doc['start_time'].value;
Note - the version in use is 6.8.