One reason a join operation cannot be processed on the server side is due to the relationship's cardinality being one-to-many and the JoinDirection being JoinDirection.Forward. When the join's left table is the origin table and the right table is the destination table, specifying the relationship's cardinality to one-to-many and the JoinDirection to Forward may result in repeating ObjectIDs in the Join table. Repeating ObjectIDs may cause many objects to behave incorrectly.