TYPO3 Core

I'm using 'label_userFunc' in TCA to adjust the row naming in the backend.
In 7.0.2 all is fine. In 7.1.0 only the uid of the row is being displayed as
long as I set 'label' => uid.
From my understanding that's according the documented behaviour:
'The result of this function overrules the label, label_alt or
label_alt_force settings.'

A bit weird:
It seem to work properly on IRRE records.
It does NOT work when record are being display as a top level recod in the BE.