fix: group rejection not filtering out invalid records correctly (#175)

Author: georgeRobertson

src/dve/core_engine/backends/base/rules.py

@@ -513,7 +513,9 @@ def process_node(node: HierarchyNode) -> bool:
         for tree in entity_hierarchy.entity_trees.values():
             for node in tree.iterate_lowest_descendent_up():
                 if node.parent_entity and node.mandatory:
-                    entity_issues_found[node.parent_entity] = process_node(node)
+                    result = process_node(node)
+                    if result:
+                        entity_issues_found[node.parent_entity] = result
 
         return [], entity_issues_found