The filter is confusing or broken

Not sure what's going on, I

• go to https://laracasts.com/discuss
• click on "Unsolved" leading to https://laracasts.com/discuss?answered=0
• now I click on "Testing" and get to https://laracasts.com/discuss/channels/testing
• the screen shows "latest" and "testing" now.

Shouldn't it show "Unsolved" and "Testing"? It also doesn't work the other way around. Funnily, it works when I construct the URL manually https://laracasts.com/discuss/channels/testing?answered=0 and then the select fields also correctly represen it.