I consider the word issue to be a loose synonym of the word problem. Can I use the word issue to refer to the scope of problems discussed in some work of art? For example, the opera's issue? By the way, can I call an opera work of art or this term can be applied only to pictures, scuptures and stuff like that?
Opera's issue does not sound correct to me, but so does opera's problem. You could say, however:
The problem of segregation is raised in this work.
The issue of racism was addressed in this play.
As for opera being a work of art, I don't see a problem with that, but work of art is usually referred to a physical object. Still:
Used more broadly, the term [work of art] is less commonly applied to:
- A fine work of architecture or landscape design
- A production of live performance, such as theater, ballet, opera, performance art, musical concert and other performing arts, and other ephemeral, non-tangible creations.