WordPress 4.7.1 was released on 11th January. It introduced a new bug that stops certain filetypes from being uploaded. This bug unfortunately stops users from uploading SVGs with the Platform 5 builder. In the meantime if you need to upload an SVG or have any other image upload issues then please try this plugin that bypasses the mime checks that were introduced.
https://wordpress.org/plugins/disable-real-mime-check/
  Link to trac ticket: https://core.trac.wordpress.org/ticket/39550 EDIT: 4.7.2 has been released without the fix. Fix is now slated for 4.7.3