When i use the Generate Unique UVs and create a UV unwrap for Channel 1 on a Static mesh the package does not get dirtied, and so you have to remember to save it manually. otherwise you can just close the editor and lose your new UVs.
This has been resolved with 4.5. We currently have the Preview of 4.5 available via the Launcher for the Binary version and GitHub for the source build.
