BUG: iPad2 UMG Material / FlipBook bug

We have our game deployed to several devices working properly. However, on one screen we have a list of (icons) generated using a particular material that takes advantage of the FlipBook node so we can store several icons in one texture file.

The Widget Blueprint along with a screenshot of what it looks like via the mobile preview can be found here: http://1drv.ms/1MSKfEC

Now, this works properly on many iPad/iPhone devices. However, our iPad2 we have, in particular, will only render icons that come from the top row (Icons 0, 1, 2 & 3). The FlipBook node does not seem to understand how to find any icon past the 1st row.

Here is a screenshot of our material: http://1drv.ms/1MSKgIK

Here is the resolution. I had to make sure the texture in particular was a power of 2. Other textures I use for UI work fine without being a power of 2, however this one in particular would not work as a flipbook/UMG material.