9.6 - .Net 3.5 Install fails on Win 8.1

Hi,
If I tick the option to install .Net 3.5, then it fails with folder not found error (sxs folder).
Do I need to download the source manually as there doesn't seem to be an option in the update generator software.
If I tick the option to install .Net 3.5, then it fails with folder not found error (sxs folder).
Do I need to download the source manually as there doesn't seem to be an option in the update generator software.