Impossible to use createTimestamp as a column in manager interface

Description

Impossible to use createTimestamp as a column in manager interface

Distribution Name and Version

Debian

FusionDirectory Version

1.4-dev

PHP version used

PHP7

Origin of php packages

Debian

Steps to Reproduce

Try to add a column createTimestamp in manager interface
The column is empty

Expected behavior:

A column with the date

Actual behavior:

Column is empty

Reproduces how often: 100%