We have disabled level duplication due to the problems with it.
In a project, if you duplicate the example level and attempt to save it, the save will finish, but the asterisk will remain on the file. Attempting to open the duplicated map will prompt another save, which will also complete, but not actually save the file. Once the duplicate map opens, you are unable to select any geometry in the level until you open the original map and then reopen the duplicate, which will prompt a successful save.
Found in 4.9.2 binary. Occurs in 4.10 Preview 2, and 4.8.3 binary. In 4.8.3, attempting to save the duplicate file will display an error message, which does not display in any of the other versions. The error reads: The following assets have been modified and cannot be unloaded: (file path of the duplicated map here) Saving these assets will allow them to be unloaded.
1. Open the editor
2. Create a new third person blueprint project
3. Duplicate the ThirdPersonExampleMap
4. Right click the duplicate and attempt to save
5. Open the duplicate map
Result: You will be unable to select any geometry in the level
Expected: The map would save successfully and you would be able to select level geometry without issue.
Head over to the existing Questions & Answers thread and let us know what's up.