Performing a ps command will display the user's uid instead of the user's name.
There is an 8 character limit with some versions of the PS command.
It will show the UID instead of the name for users that have a username that is greater than 8 characters in length.
This is a 3rd party issue and therefore it will do this for local users as well.
Some versions of ps allows formatting of the output.
Please see the man page for ps for your operating system platform.