Launch in browser causes panning material to smear

Can someone help with this! When I launch this test in Chrome or Firefox the panning background material smears as it scrolls. There’s no lighting in the scene, the sky material is emissive - thought this might have something to do with it but I’ve tried it as a normal material lit with a spot light and the same thing happens… Plese ignore mad pixelation.

Ok, got an answer elsewhere - the size of images used have to be a power of 2. Working now!