I just started case where the report is inappropriate user name, however I cannot act on it because I can not see the user name in question.

That's an ongoing glitch or something, without evidence you can only skip or pardon for the time being.

It should display the name up at the top in under the original inappropriate name when it does work but the logs will still display as annie and etc

it says it directly below the reason for reporting

^It should say it, but I have had a few cases where the report bugged out and didn't include the name.
In one case, the report didn't include the chatlog either. That was weird.

Copy the case number and send in a support ticket.

This is a known issue that has been posted in other threads. Hopefully it will be fixed soon.