So, it isn’t the only game I’ve had issues with, but I’m currently trying to play FFXV and sometimes Z3D works, sometimes it doesn’t… If I go to graphics settings and mess with the resolution %, sometimes it works at 100%, sometimes 200%… switching between borderless, off and on in the fullscreen display setting also seems to randomly turn the zbuffer off and on…
Some games change/recreate the depth buffer texture during gameplay, which can be diffiult to detect. I don’t recall FFXV to be such a case, but I’ll check it. No promises though, such issues can’t always be reliably fixed.
What you could try on your end is checking whether running the game windowed/fullscreen makes a difference. Same for with/without antialiasing.