For some users, the Date/Time field is showing 'Empty' as this value for blank field:
This is the result when the user's setting for Date/time has been selected as 'Time Ago'
To update to this setting:
In an OOB instance, if the value for Date/time has been selected as 'Time Ago'. On the Incident form, for NOT 'Resolved' or 'Closed', the value is '(empty)'. Therefore, to see the blank value: