Hi!
During packaging, UE4 not analizing levels. For optimize package size, try this
- Create blank project without starter content.
- Open your working project.
- Select needed level in Content browser, press right mouse button and select Assets Actions -> Migrate. Level and only needed assets migrate to new project.
- In folder dialog select folder Content in your blank project and press OK.
- Open project in which you migrate level. In Project Setting -> Projects -> Maps & Modes -> Default Maps add your level.
- Package project.