Fixes for Warahouse 4.2.1 theme
Add following css on 
Advanced Styles (CSS)  backoffice module configuration
@font-face {
  font-family: 'Material Icons';
  font-style: normal;
  font-weight: 400;
  src: url(../fonts/MaterialIcons-Regular.eot); // For IE6-8 //
  src: local('Material Icons'),
     local('MaterialIcons-Regular'),
     url(../fonts/MaterialIcons-Regular.woff2) format('woff2'),
     url(../fonts/MaterialIcons-Regular.woff) format('woff'),
     url(../fonts/MaterialIcons-Regular.ttf) format('truetype');
  }
  
  .material-icons {
  font-family: 'Material Icons';
  font-weight: normal;
  font-style: normal;
  font-size: 24px;  // Preferred icon size //
  display: inline-block;
  line-height: 1;
  text-transform: none;
  letter-spacing: normal;
  word-wrap: normal;
  white-space: nowrap;
  direction: ltr;
  
  // Support for all WebKit browsers. //
  -webkit-font-smoothing: antialiased;
  // Support for Safari and Chrome. //
  text-rendering: optimizeLegibility;
  
  // Support for Firefox. //
  -moz-osx-font-smoothing: grayscale;
  
  // Support for IE. //
  font-feature-settings: 'liga';
  }
Unzip attached file 
MaterialIcons.zip into  /modules/pm_advancedpack/views/fonts folder
Unzip attached file templates.zip into /themes/warehouse folder
or if you use a child theme unzip it into appropriate folder eg. /themes/warehousechild