Not sure if this is a me issue or not, but I was getting an error with 1.4.4 saying it couldn't find the "NativesTableList_UDK-2012-05" for exporting classes.
So I went to check and the file was in the correct location, then I noticed that it was looking for "NativesTableList_UDK-2012-05." and not "NativesTableList_UDK-2012-05.NTL" so I removed the extension and the exporting worked fine.
I'm on win10 and I was exporting the borderlands 2 engine.upk classes.
https://i.imgur.com/rJqRRUH.png