Hi, eevan.
Looks like you didn't put any value on the custom field before saving it, right? If you had, there would be a date there on the
#value# attribute, like this:
Code:
"#value#": {"__value__": "2019-09-25T12:31:45.812000+00:00", "__class__": "datetime.datetime"}
The full date set in this example is the bold text. If you edit this on your files BEFORE adding to calibre, it will be imported automatically to the #original column.