To reproduce:
1. Create a plane
2. Create a new material
3. Add a texture to the material (Albedo)
4. Set the tiling of the material to be 10x10
5. Add the material to the plane
6. Deploy to a Lumia device with a software navigation bar (WP8.1 or WP8)
7. Notice the plane is looks completely different from the editor

The issue is related to the filter mode, setting it to 'none' solves the problem

Does not reproduce with Version 4.6.3p1

This seems to be another driver bug (I've been able to reproduce this on Lumia 830). Texture doesn't look right because it's clamped instead of wrapped (reducing tiling from 10 to 2 allows to see effect easier). This can't be really fixed except in the driver.

However I have found workaround that fixes standard shader. All you need to do is change this line in UnityStandardInput.cginc file from:

sampler2D _MainTex;

to:

sampler2D _MainTex:register(s0);

You can copy Standard.shader and corresponding UnityStandard*.cginc files to your project and do modification there to not affect other projects. Our graphics team doesn't want this workaround enabled on all platforms (understandably) but it can save Windows Phone projects that are affected by this.