I'm not using individual icons, they are all taken from that icon block you linked to. Google Earth is supposed to be able to use 'blocks' of icons like this. This is deliberate to save downloading lots of fiddly little icons and I am following their spec exactly in doing this.
You will have to complain to Google to find out why it's not working. It works for me so I suspect it is something to do with the abilities of different video cards. Very annoying, sorry.
I do intend to split up the download but have been busy with other things on the Portal. Glad to see people are using it, I will get to it in due course.
Something is not right. This message is just to keep things from messing up down the road