Create_date in list views Sao client hangs

Hi,
the moment I use create_date, the internal field in list view, the view will not load, and the clients shows the “processing” note. There is no error logged. even if I wrap the crate date inside a function field

created_at = fields.Function(
    fields.DateTime("Created At"),
    'get_created_at',
)

def get_created_at(self, name):
    return self.create_date

the behavior persists. Intended, wrong approach, bug?
Thanks in advance
Regards Jakob

There is no datetime widget on tree view, you must define the column either with a date or time widget.