Sublevels appear dirty when the level browser is closed and re-opened.
1. Download attached files
2. Open Editor (any project)
3. Open World Settings, enable world composition browser
4. Open Levels Editor
5. Import tiled landscape (downloaded files)
6. Load and save new sub levels
7. Close level editor
8. Open Level Editor
Head over to the existingAnswerHub thread and let us know what's up.