You can compare your Unity Player Settings to the ones in this FAQ:

https://developer.vuforia.com/forum/faq/unity-player-settings

For me Automatic Graphics API is unchecked and preset to OpenGLES2 but I still have this issue on the S6.

The only other options in dropdown list is metal and OpenGLES3

I was wrong - Graphics APIs is set to OpenGL ES 2.0 is what i needed o do it should be noted you have to subract es3 from drop down menu!!

I have exact same problem unity 5.1.0p1 armv7 setting, and es2 dont resolve for me using vuforia 4.2.3

Yup, that did it. By default "Automatic Graphics API" is checked. Unchecking it and telling it to only use OpenGLES2 solved the issue for me. (Samsung S6)

Thanks for confirming.

Vuforia 4.2 officially supports OpenGL ES 2.0, so if this settings is not already set, you will need to change it in the Player Settings. 

I think it was OpenGL ES 2.0, because I set Device filter as ARMv 7 all the time.

Can you confirm which setting in particular fixed your problem ?

The OpenGL ES 2.0 graphics settings  or the Device filter ARMv7 ? 

Hi

I just ran the test, and it works fine with those settings. Does it mean we need to apply these settings for Unity 5.1.0p1 for now?

OK, thanks for confirming this.

Could you verify the following Player Settings (Android):

- Graphics APIs is set to OpenGL ES 2.0 (if it is set to Automatic, could you change that and make sure to include OpenGL ES 2.0 only ? )

- Device Filter: must be set to ARMv7 (and not to FAT (ARM v7 + x86)

I just installed and ran the Image Target scene from your samples and it does the same thing. Here is a screenshot:

https://dl.dropboxusercontent.com/u/17584871/Screenshot_2015-06-22-12-16-24.png

I think it would be importatn to establish on what Unity 5.1.x version this issue has been observed;

The recommended version to work with Vuforia 4.2.3 is Unity 5.1.1f1 (released on June 18th) or newer; older versions (such as Unity 5.1.0) may not work correctly .

And as I asked previously, it would be important to know whether this issue can be reproduced using one of the Vuforia Samples.

Hi dereklam,

I encountered the same issue when I upgraded to Unity 5.1.

My recommendation is to revert back to Unity 5.0.x and you should be fine.

can you reproduce this issue using one of the Vuforia Samples ?