The editor is not allowing users to save or close a project after an .FBX file has been copied to the project's Content directory and allowing the Content Browser to discover the change in source files, and importing through that method.
This process of importing is not an incredibly common workflow that I know of, but it still seems to be used enough to affect a number a users.
Regression
4.15.3 - 3450819 - Does Not Occur
4.16.2 - 3514769 - Occurs
//UE4/Main 4.18 - 3521054 - Does Not Occur
1. Create new blank project.
2. Copy the attached .FBX file into your project's Content directory.
3. Return to project and Import content once prompted by dialog window (image attached)
4. Save All.
5. Attempt to exit/close the editor.
Outcome The editor remains open and seems to ignore any commands to save and/or close. The user must force close the application.
Expected The editor saves the imported asset and level, and you are able to close the application.
Head over to the existing Questions & Answers thread and let us know what's up.