windows 8.1 tile background and image is not set correctly

There are 2 key points:

1. You need IE to be your browser by default. Or the live tiles are not updated. Even if it was your browser by default and the tiles were live, once you make chrome, opera or any other browser your browser by default live updates will stop.
2. IE should be in a metro mode. If its in a usual mode, the favicon will be retrieved and browserconfig.xml or any metategs are ignored. Also tile background in this case is set by favicons color(not sure how it is calculated, but depending on the color of your favicon the color of the tile will be set).

You can find more details in the github issue.