Well, i do remember that Jezze did fix this bug, but only for d3d. Why he did it only for d3d, are reasons i dont want to explain here in detail. It was expected that someone transfer HLSL to BGFX and so Jezze never touched the BGFX part.
While excessive HLSL testing, Jezze and me found that bug (that existed even for d3d mode) two years ago and we reported that.
It was said, that Jezze created that bug, by his overhaul changes in MAME 0.160 (could be 0.161 or 0.162, cant remember it exactly), which of course was not true, but he fixed it.