I have a D7 instance with a field collection called field_professions and associated to a content type with "unlimited" amounts of fields. Within this field collection I have two fields that are required (field_professional_user and field_professions). I also have an unrequired field called field_serving_since. For the sake of testing I made the entire field collection required.
Now, when I have an item entered, I can enter a 2nd, 3rd etc. item, but whether I fill out all 3 fields, 1 of the required fields, or the unrequired and none of the required fields, it never validates that the fields are required. I can obviously see the red asterisk, but there is no validation.