I don't know if anyone noticed this, but when "User 1" creates a topic as Anonymous, and then "User 2" adds a post, the home page still shows "Anonymous" in the last post column.

Tested on 4.7.19 on default theme.

As you can see, User 2's avatar displays correctly, but his username does not.

Thank you for bringing this issue to our attention! I can confirm this should be further reviewed and I have logged an internal bug report for our development team to investigate and address as necessary, in a future maintenance release.