SphereMask node working wrong on mobile

Have simple material with SphereMask, in windows it working perfect, but on mobile have wrong results.

Material

In Editor preview

On Moblie device (iOS 8.3, iPhone 5s)

Hi BorodMorod -

Thank you for your report. I was able to reproduce the issue internally and have reported it as UE-16307. We will keep you informed as we investigate a solution.

Thank You Again -

Eric Ketchum

The bug came back as ‘Won’t Fix’ as this was related to a mediump precision issue. The best fix we determined for this would be to ensure this material uses full precision. We will be adding a feature within an upcoming release to allow users to account for the full precision within their materials. This should resolve the issue.