the same thing: some colors are dropped
thee background of rough is the same #808000 as the original, no problem with that. the problem is the background of custom/rubble: if it's between #414100 and #7f7f00, then it's converted to #808000, and if it's #404000 or darker, than it's converted to #000000Another test would be to use a lighter background for rough as both background looks too similar.
so it seems to be a palette issue, the built-in colors are limited in suite. it's not a problem if you can tell which colors can be used (export the palette)