For me, this will give a black screen when view is set to internal artwork cropped/stretched:
mame64.exe mslug -video bgfx -bgfx_backend d3d9
Fine on other bgfx backends, fine on MAME's own d3d (which is also d3d9).
Probably the cause:https://github.com/mamedev/mame/com...36#diff-51c257589922bc47b022aa4045c68ed8
There's nothing wrong in this .lay file though.
here's another one where the screen gets blank, the chessboard screen at the top-right
mame64.exe ccmk5 -video bgfx -bgfx_backend d3d9