Autodesk officially supports only 3 versions back - both in saving and licensing. And they recommend plugin developers to do the same. So right now, we cannot legally run any max older than 2015, which means we could not debug any max 2014-specific bug should it happen. We still provide 2012-2014 in the installer as is. We would like to drop 2012 support at some point, because 2012 vs 2013 is much bigger APi change than any newer updates, which causes us some pain and makes the development slower. The usage stats show that 2012 and 2013 are hovering at few %, but 2014+ is still widely used.