The grid expects FontAwesome to be available, as the core CSS utilizes a subset of the icons for things like sort-arrows and grid action icons.
The grid component doesn't ship with fonts since that's a bad practice. For the grid to work correcrly, you will need to make FontAwesome available either via build process, or linking to them externally. Here is a list of all icons currently utilized by grid:
icondictionary = {
'arrows-v': '\F07D',
'search': '\F002',
'close': '\F00D',
'chevron-down': '\F078',
'chevron-right': '\F054',
'filter': '\F0b0',
'action': '\F142',
'sort-up': '\F0D8',
'sort-down': '\F0D7',
}
Please see font awesome's documentation for more information