diff --git a/backend/services/data-management-service/src/main/java/com/datamate/datamanagement/application/KnowledgeItemApplicationService.java b/backend/services/data-management-service/src/main/java/com/datamate/datamanagement/application/KnowledgeItemApplicationService.java
index 1358693..1baafef 100644
--- a/backend/services/data-management-service/src/main/java/com/datamate/datamanagement/application/KnowledgeItemApplicationService.java
+++ b/backend/services/data-management-service/src/main/java/com/datamate/datamanagement/application/KnowledgeItemApplicationService.java
@@ -266,6 +266,12 @@ public class KnowledgeItemApplicationService {
         response.setTotalKnowledgeSets(totalSets);
 
         List<String> accessibleSetIds = knowledgeSetRepository.listSetIdsByCriteria(baseQuery, ownerFilterUserId, excludeConfidential);
+        if (CollectionUtils.isEmpty(accessibleSetIds)) {
+            response.setTotalFiles(0L);
+            response.setTotalSize(0L);
+            response.setTotalTags(0L);
+            return response;
+        }
         List<KnowledgeSet> accessibleSets = knowledgeSetRepository.listByIds(accessibleSetIds);
         if (CollectionUtils.isEmpty(accessibleSets)) {
             response.setTotalFiles(0L);
diff --git a/backend/services/knowledge-graph-service/src/main/java/com/datamate/knowledgegraph/domain/repository/EditReviewRepository.java b/backend/services/knowledge-graph-service/src/main/java/com/datamate/knowledgegraph/domain/repository/EditReviewRepository.java
index 6bfc3fa..7ae299a 100644
--- a/backend/services/knowledge-graph-service/src/main/java/com/datamate/knowledgegraph/domain/repository/EditReviewRepository.java
+++ b/backend/services/knowledge-graph-service/src/main/java/com/datamate/knowledgegraph/domain/repository/EditReviewRepository.java
@@ -43,7 +43,13 @@ public class EditReviewRepository {
         params.put("reviewedBy", review.getReviewedBy() != null ? review.getReviewedBy() : "");
         params.put("reviewComment", review.getReviewComment() != null ? review.getReviewComment() : "");
         params.put("createdAt", review.getCreatedAt());
-        params.put("reviewedAt", review.getReviewedAt());
+
+        // reviewed_at 为 null 时（PENDING 状态）不写入 SET，避免 null 参数导致属性缺失
+        String reviewedAtSet = "";
+        if (review.getReviewedAt() != null) {
+            reviewedAtSet = ", r.reviewed_at = $reviewedAt";
+            params.put("reviewedAt", review.getReviewedAt());
+        }
 
         neo4jClient
                 .query(
@@ -57,8 +63,8 @@ public class EditReviewRepository {
                         "    r.submitted_by = $submittedBy, " +
                         "    r.reviewed_by = $reviewedBy, " +
                         "    r.review_comment = $reviewComment, " +
-                        "    r.created_at = $createdAt, " +
-                        "    r.reviewed_at = $reviewedAt " +
+                        "    r.created_at = $createdAt" +
+                        reviewedAtSet + " " +
                         "RETURN r"
                 )
                 .bindAll(params)