dezipped, opened the map id3d, saved, rezipped and nothing change. No yellow on the pda for my sesame field.
Can't it be a giants limit ? they have for everything so they are able to limit the pda colors to 32 or smth like that.
Indeed, weird thing. I can see color changed after editing the value in the foliage xml but nothing on the map. Starting a new game isn't a solution. At first I thought that the problem was you had only 3 values in the mapcolors (supposed to be 4 no ?) but adding a 4th didn't fix it in my test.
Btw, I saw on the map xml you have twice "animals" and "additionalfiles" blocks, it's time to clean up a little ;)