Some part features that regenerated in SW2013 fail when opened in 2014 and 2016.  One part is fine in 2013 and 2016, but fails a feature in 2014.  Is SW not fully upward compatible?

Examples of (4 different parts) features that fail when opening 2013 parts in 2014 & 2016.

1.  A cut to surface fails due to a surface extend produces different results in 2014 than in 2013.

2. A round fails to regen in 2014, but works in 2013 and 2016

3. A mirror body fails to regen in 2014 & 2016.  However, If I create a new mirror exactly as the failed mirror, in 2014 & 2016, it works.

4. A circular pattern fails to regen in 2014 & 2016