The glitch here is due to texture UV addressing mode being set to “clamp to edges” instead of “repeat”. Try checking if this happens also on Firefox. Also, try replacing the texture with one that is a power of 2 (256x256, 512x512, 1024x1024, …) if it is not already. Check if there are any errors or warnings in either the console log window on the page or in the browser’s console. Last, try out WebGL 2 support once it lands in UE 4.16, it is possible that WebGL 2 might avoid the issue directly.