We use multiple sites on our EE installation.
On the main login page, you see “Recent Entries” on a one site that refer to another. When you click on them, it fails as it cannot be found which is expected.
However, is this not a bug. Why show such data on an unrelated site and then just generate an error from it? Should that page not be showing content specific to the site you’re selected into?
I’ve replicated this and confirmed the issue. I’ve also opened a bug report where you can follow when this is resolved. https://github.com/ExpressionEngine/ExpressionEngine/issues/1102