It seems that as now dimensions are associated to the geometry (“by default”) even using TAB to restrain then during their creation, if you modify one of them, they update and align to the line connecting the two elements snapped during its creation. It’s not bad, is just a new “feature” that needs to be understood.
With the old behaviour, sometimes I used aligned dimensions by default, because they let me dimension elements in any situation. Now, in RH6 I will need to stick to the dimension type that needs to be used on each case. It’s not a big drama, is just different (I thought that was a bug).