As I understand, this is a regression, since Diablo used to work a long time ago, and then some patch broke it. The bug was opened sometime in March...
Can you tell us exact date, please, at which the game worked? If I would knew this, I would already was doing several-years-wide regression test.
When I say it used to work, I am basing this on what you've written in the bug - I hadn't personally tested Diablo until recently, at which point I confirmed your bug, since I am experiencing the same behavior.