Directx 12 does not show Steam FPS overlays and MSI Afterburner overlay. It's just that. It's not a problem with the program or overlay, other games work normally with this overlay, including The Witcher 3 using Directx 11.
DX12 is absolutely supported by both the Steam overlay and MSI afterburner. Had the same issue with RTSS not working in CP2077 a while back. Re-installing Afterburner and RTSS fixed it.