Custom report expressions are not processed correctly

I mean, I couldn't find any documentation or any example to compare with, but any expression I put in the box is not processed when accessing worklog data. If I put, for example, "this" keywork, in the column I can read the Json of the current object, but there I cannot extract any fields value if I refer to any property.

My intent was to extract the "worklog.updated" field in the report, but every attempt result in empty cells