OK, I looked at the full file and again everything played back fine for me. Some of the volume levels in the Mixer seemed kind of soft, but they did playback.
Is there any particular reason why you aren't letting the non percussion instruments playback through Sibelius Player? I tried that also and it seemed to behave like it's supposed to.
None of the screen shots you attached are showing any settings that are out of whack. We may need to dig deeper into your overall setup. What hardware are you using? Sound card, speakers, etc.