depends on where you're going with the back-button (that page maybe has no cactive conversation scope) or - if it is the same page. It was not a long running onversation in the first place.
Basicall: only annotating a bean with a scope is not enough, if you don't explicitely put a statement somewhere that you want to have a long running conversation. So, or a method with abegin annotation, or a page descriptot with an additional attribute, or programmatically pushing the long running conversation.
I think that you can lazy initialize only entities which are attached. And they are not if you hit back button to page where is lazy initialization of lists attached to before loaded entities (these entities are detached already so no no lazy). Simple workaround is to use long-running conversation or eager loading. In general I hate usage of back button in seam app.