I am running CiviCRM 4.7.27 on WP 4.9.1. This is a multisite and I am seeing some odd behavior when composing an email with CiviMail regarding the "Groups" available recipients listing. For non-admin users of one any one of the sites, they are not getting the group they are permissioned to see when composing a CiviMail. I am not seeing any patterns on why they are seeing only the same 3 groups (we have over 50). Those 3 groups are tied to different organizations.
Is there a certain way this is supposed to be permissioned? How does civimail determine the group recipients for a multisite domain?