Which side is the FK side, Order or DeliveryAddress? I think 'Order' ?
The FK side has the same number of fields as the PK side. I'm very surprised you could create that relationship in v2, as it would have a hard time generating the relation code because there's no matching FK field for 'AddressType in 'Order' (and the custom relationship editor requires for every PK field an Fk field to be specified in v2.x) It would otherwise be a m:n without an intermediate entity, something we don't support (nor did we do that in v2). To be a 1:n/m:1 relationship, the FK side has to have all PK fields, in v2 and in v3.
If you can't change the db, be sure to set the '...FollowDB...' settings to false in project properties.