I wonder whether it has something to do with your username as that one includes a period.
I'm not even able to create an account with a . included on my X440.
Maybe try it with a username that doens't include special character.
As per Thomas suggestion... ssh into Netsight so that you are in the CLI shell.
Then from the Netsight CLI try to ssh to a switch.
In your above screenshot the putty session is going from your laptop to the switch and not from Netsight.
Could you please also provide a "show management" and "show vlan" from the test switch.
Can you go onto the netsight server directly and try to ssh to that particular device? There could be acl/policy/firewall in the way. The device could have ssh disabled or locked out as well.