Maybe I don't know how to use Help on the Adobe site but I couldn't find anything about this topic (which I'm experiencing too) so I finally just did a Google search and this thread came right up. Grrrr.
Dittos on the complaints because I've wasted a lot of time on this. First, trying to figure out what I was doing wrong, then finally going back to the previous version of PS to find out that it still works there and it must be a bug in the 2014 version.
It sure would have been helpful of Adobe to send out a notice to their loyal user base telling us about this bug. Were they embarrassed or something and thought we wouldn't notice it? I mean what could they have been thinking? They're smart people and are used to putting themselves in the user's place. I use Auto-Blend all the time in my work and was really going nuts when it wouldn't work. Adobe MUST know how useful this relatively new feature is and that a whole lot of us use it now regularly. Maybe we're spoiled but, hey, they made the darn thing so they should know we've come to depend on it.
Blend on fellow users!