If you have a relationship that is mapped to a value that is a relationship then if you have an import<;attribute;> in the relationship class, it will not be triggered.
See http://stackoverflow.com/questions/21441329/magicalrecord-importattribute-not-working-for-relationships for more information
I've just made a bunch of changes around data import — could you retest this against the develop branch (or release/3.0 if you're testing MagicalRecord 3)? Thanks!
I'm confident this is fixed in 2.3, but please feel free to re-open this issue if you've tried and it's still happening under MagicalRecord 2.3.