The abilities does not add up to the ACE score - is this correct?

Yes, this is perfectly normal. There are three primary reasons why the mean of the sub scales or Abilities' scores does not equal the ACE score.

First, the main reason is that the Abilities are normed separately from the ACE total score. The difference is relatively small close to the middle scores (4,5,6 or 7) and larger close at the ends of the STEN scale (1,2 or 3). Second, Metis calculates scores for Abilities separately from the total score. While the same items are used, the ACE total score is not calculated as an average of the Ability scores. The ACE score is calculated first, then the items are divided into three groups and then the Ability scores are calculated. Finally, when the STEN scores are calculated they are rounded off from an underlying Z-score. If these fall in a certain way - for instance Abilities are rounded down but the total score is rounded up, this can also cause some of the differences some people might see. Additionally, any score below STEN 1 or above STEN 10 will be rounded up or down, respectively. This means that an ACE score of 1 could be “hiding” a lower score, lowering the mean more than what can be seen.