AFAIK, there was Word 2010 and Word 2013. No Word 2012.
However, the versions have handled envelopes the same way since Word 2007, at least.

See Change Envelope Layout by Graham Mayor, MVP

If you wish, create and save an envelope that will not work for you as a document and attach it to a post here.
Attach a Sample File Demonstrating the Problem - Here's How