Album Content Notifications

I recently noticed that if photos within an album get any kind of interactions that would normally send the context owner a notification, it doesn't.

When someone comments on a photo within the album, no notification.

If someone leaves a like on the photo within the album, no notification.

The only time when someone gets a notification about the album (not its contents) is when someone comments or likes the overall album itself.

Is this a bug or intended?