I have been trying to setup automation to set the value of a Rating field to "3". When creating the rule, the field is not found, so I'm creating an advanced update of the issue.

And then using the following rule, and I tried with value to be "3" and 3.
{
"fields": {
"Urgency": {
"value": 3
}
}
}It provides the following error log:

So I tried to find this custom field in administrator view, but this field is not possible to locate in https://<domain>.atlassian.net/secure/admin/ViewCustomFields.jspa
My conclusion is that the value is something else than just a value, but I cannot find the field to figure out the structure, so I'm screaming for help 
Any ideas?