Is FMatrix 4x3? Where's the 4x4 matrix?

[anonymous_user_c8cdff6f]

Thanks! I can confirm that FMatrix set this way to 4x4, works when sent to a hlsl shader via DECLARE_UNIFORM_BUFFER_STRUCT_MEMBER().
Really strange that the same matrix data struct has weirdly specific different sizes. And this whole FMatrix and FPlane vs FVector4 is just bad programming UX.