Just rebuilt to MAME 0.234 to test it out. Set video to bgfx and bgfx_backend to vulkan. MAME launches and runs (mangohud confirms vulkan in use) but then the video freezes after a few seconds. Emulation continues however. I can run pacman and insert coins and press start and I hear the coin sound and the start music. There are just no video updates. Double checked to confirm: no such issues with the opengl backend, the video continues normally.