Thanks Matthew! You were right – even though I’d deleted and reinstalled UE4 from the launcher, some files were left over, and this particular file was read-only. Deleting the entire 4.11 folder and reinstalling it fixed the issue. Thanks again 
Thanks Matthew! You were right – even though I’d deleted and reinstalled UE4 from the launcher, some files were left over, and this particular file was read-only. Deleting the entire 4.11 folder and reinstalling it fixed the issue. Thanks again