OK, the first issue, with the grouping, is that the element you are grouping on, app_mob_animal___mob, is in a repeated, joined group. So it's from another table, which has a one-to-many relationship. So Fabrik is grouping it accordingly ... if an animal has 3 entries in app_mob_animal, then it's grouping by those 3 entries.
To group by "current mob", you'd need to have a single field on the main table, which specifies the single "current" mob.
-- hugh