Can’t check on Mac.
Verified on Windows 10 and Linux (Archlinux + Gnome). Here are results Linux (Vivaldi 2.3.1440.41): none of Lock options work except “On Browser restart” Windows (2.3.1440.48): only two options work: “On Browser restart” and “On system lock”
Works properly in Chrome and Firefox on aforementioned machines.
I’m experiencing this same thing with Vivalidi on Linux. Its surprising that this issue has been around this long. Maybe the right people just haven’t seen it yet…