Windows 10 Public key w/o pass-phrase [1]

HI, I have set up Xshell to run a local socks proxy. It works with a password, but I cannot for the life of me get the public key with or without a passphrase to. I get the message (see attached) "user key not registered in remote host". I have reinstalled both Openssh for windows and Xshell. Openssh is installed as the server with "separated privledges", I have created the ~/.ssh folder and saved the public key as authorized_keys. I'm at a loss. I have recently reinstalled windows, however nothing has made a difference. Any insight would be appreciated.
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Program Ver. : Xshell 5

UPDATE: resolved
After much fiddling, I followed the instructions here: http://www.mls-software.com/opensshd-pki.html to modify the sshd_config as described above. Hope this helps anyone else who might have been having problems. (this was a clean install of windows 10, I'm not sure I had to do this step previously).
thanks