I ran into the same problem on windows 10. I fixed it by doing the following steps.
1:- Right-click on the target file and select properties then select Security Tab
2:- Click Advanced and then make sure inheritance is disabled.
3:- Click apply and then click Edit in the security menu
4:- Remove all users except Admin user, which should have full control
*Admin account should have all checkboxes checked on Allow column except
special permission.
5:- Click Apply and then click OK.
You are good to go.
This worked for Amazon EC2 .pem file and gave almost the same working as Chmod 600 on Linux.
