Hi Michael.
Thanks for your reply. I have not used the Global ID as the related field; instead where are using the ID that our organization assigns to the record when it is created - we call it the 'Case Number'. Within the feature service, we have one feature class and three related tables, and all the relationships are based off of 'Case Number'. For two of the tables the related table data displays as expected in the Attribute Table. It's just that one table - with the subtypes and domains - where the data are not displayed.
I'd be happy to share the feature service URL with you directly, however, it is private to our organization though and i don't think i can make it public. Is there a way that i could add your account on a temporary basis to our org account? or some other way to grant you access?
Thanks again,
Tom