Mindstorms EV3 3D building instructions no longer working in Chrome
Google deprecated support for NPAPI in April this year, and removed it completely this month in Chrome 45.

LEGO has historically used Unity Web Player for a number of their online 3D games which has certainly been impacted by this change, and while this is not specifically the case here (the building instructions are "Powered by Autodesk Technology", possibly a variant of A360), it's probable that the underlying cause is the same - the plugin uses the older technology that Google is removing.

They do still work in Firefox if that helps.