Screen Tearing with Vulkan Mailbox Present Mode on Fullscreen
It's hard to see how it could be anything other than a driver bug.
Unless maybe it isn't vsync screen tearing at all, and is just something that looks similar enough to have tricked you. e.g. Maybe you're missing some important bit of synchronisation and you're changing a texture/vertices/uniforms midway through the screen being rendered. Or maybe there's a bug in your logic somewhere and you're rendering to the on-screen framebuffer instead of the offscreen ones.
I tested the app on my second computer. Strangely enough, it works perfectly fine without any tearing. Using same Nvidia driver but with a Titan XP.
So at least I know the code is working. On my main computer I reinstalled the latest Nvidia driver and tried to disable any services on the computer that could be causing issue but nothing helps.