This is an issue affecting a site I’m working on as well. Not entirely sure why only a few users get affected by this. But this issue is definitely an old one. I had to force specific author slugs back to what they were because of this issue.
Just going to point out that you can pay someone that’s spent time to actually learn how to use WordPress to create a custom WordPress theme to suit your needs. I’m not trying to be rude, but you certainly were and it doesn’t really help the community. If there is something wrong with the software, create a ticket, if it’s broken of course. There are many ways we can contribute. Lastly, you’re using the WordPress default themes, just like any theme developer, they leave their ‘attribution’ on their work. You’re not paying for it. If you do buy a theme, the theme developer will usually sell support for the theme and sometimes even try and bend over backwards for you. However, this is not the case here.
Point: Purchase a theme that meets all your needs.
