The outer most hitbox on his down-tilt begins pretty far into the z-axis which effectively makes the strong hit come out a frame later in many instances. Creating situations where it looks like it should hit but it does not. In this scenario the inner 2 hitboxes would connect on this frame.
I can’t find the patch note but I’m pretty sure it was Slade’s forward-air (It might be a different character and/or move) that got adjusted previously for the same reason.

so thats why this move sucks