Go to Tools>Options>Theater View and look the Items To Show list, find the Item "Audio" and click on it, then click on "Set Rules for File Display" and make sure the "media sub type" is set to show "Audio", also check the same for the subviews (such as Album, Artist, etc.). Only the parent view "Audio" needs the media subtype = audio rule (parent rules apply to subViews) but you need to see if there are any rules applied that your actual media is not following thereby preventing it from showing.
There must be a tag in your Classical Music that is preventing the Theater View from displaying.
