When I fight a mob and defeat him. Normally those experience balls will be dropped to gain levels.

But they don't get rendered/I don't see them. But when I come close to where the mob was defeated I can hear that they are picked up.

I have made a video, but it's 17 MB so I can't share it.

Hope this description is enough.

I have searched the known issues page, but I can't locate that this is reported.