I was able to get the icons to show up locally in the WP8.1 emulator and device by following this method:
Specifically, removing the querystring from ttf font-face declaration worked for me:
url("#{$ionicons-font-path}/ionicons.ttf") format(“truetype”),
//url("#{$ionicons-font-path}/ionicons.ttf?v=#{$ionicons-version}") format(“truetype”),