It may not be displayed correctly texture mobile terminal When you use the normal map with a blend material

I am relying on the automatic translation because can not English.
Please forgive me if the sentence is funny.

I have developed a mobile game to use the UE4.
There is a serious problem in the blend material using a normal map in UE4 ver.4.11(ver.4.12preview as well).

Texture is not displayed correctly on a mobile, it would be displayed as block noise.
However, in UE4 ver4.10 texture it will be displayed properly.

The following shows the material.

As shown in the figure above

Color texture x3 (Tex1 / Tex2 / Tex3)

Normal texture x1 (applies to Tex1)

In the case of, the texture in the mobile (Tex1) is not properly displayed.
By the way, Tex2 and Tex3 are normally displayed.

In UE4ver4.10, all the textures had been successfully displayed on the mobile.

However, if the next of materials, textures, even UE4 ver4.11 are displayed properly.

Is this a thing by design change of ver4.11?

Or a bug of?

Please tell me you know who.