UBB.threads PHP Forum Software Community Forums UBB.threads 7 Bug Reports Percent sign in Subject

I've noticed if one puts a % sign in the Subject at at forums.applecentral.com if one tries to click on that post it gives;

Bad Request

Your browser sent a request that this server could not understand.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

OS X Safari and Firefox.

UBB 7.5.8 but it has done the same in earlier versions too.

Seems to be a problem at forums.applecentral.com, it works here though, tested in this thread;

https://www.ubbcentral.com/forums/ubbthreads.php/topics/255113/__sign_working?#Post255113