Thanks for this question.

I have been able to give the good answer only because I remembered a SQL Server Days session about différences between columnstore indexes in SQL Server 2014 and in SQL Server 2012. The speaker learnt me that there were 2 DMV giving the repartition in row groups in 2014 instead only one on 2012. So the answer was evident.

I must admit that I have not deeply studied columnstore indexes in the 2012 version and not all in the 2014 one.