Comment 75 for bug 1296270

16.04 LTS.

I tried a few different options in: "Brightness + Lock" but had no luck. The settings there do affect this issue, but I could not turn off the old style lock (disaplyed here: https://askubuntu.com/questions/639014/another-password-prompt-when-waking-from-suspend ) without uninstalling gnome-screensaver.

Uninstalling gnome-screensaver, like the askubuntu.com link suggested fixed the issue for me.