Image effect (post-processing) + Anti Aliasing Disabled = Blend problem

Hi, I have an image effect with "Blend SrcAlpha OneMinusSrcAlpha", which works if QualitySettings > Anti Aliasing is **not Disabled**. However, if it is **Disabled**, the effect is **as if the destination's Alpha is always 0**, i.e., - if source color is fixed4(1.0, 1.0, 1.0, **1.0**), the result is **white**, - if source color is fixed4(1.0, 1.0, 1.0, **0.0**), the result is **black**. Thanks!