Materials break after lighting build

I’m making a visualiser for a random music program - moving horizontally, one square from each row turns a different colour, as a section of music is played. It all works but when I build the lighting the materials seem to break, and display a black and grey pattern of squares, the default non texture - except for the first one, weirdly. I’ve created a different material for each row and tried to using material instance too, but still the same. I’m sure there’s a simple answer to this but I can’t see it!

So it’s something to do with texture samples - materials with texture samples 1/16 don’t work and ones with 3/16 do. So I’ve duplicated the working ones and modified them - I’d just like to know why this is? What do the texture samples have to do with it? I’ve got it working now but I want to know why :smiley: