diff --git a/lib/ops/message-store-ops.js b/lib/ops/message-store-ops.js
--- a/lib/ops/message-store-ops.js
+++ b/lib/ops/message-store-ops.js
@@ -158,30 +158,29 @@
         };
       }
 
-      if (messageStoreOperation.type !== 'replace_threads') {
-        return messageStoreOperation;
-      }
-
-      const threadMessageInfo: MessageStoreThreads =
-        messageStoreOperation.payload.threads;
-      const dbThreadMessageInfos: ClientDBThreadMessageInfo[] = [];
-      for (const threadID in threadMessageInfo) {
-        dbThreadMessageInfos.push(
-          translateThreadMessageInfoToClientDBThreadMessageInfo(
-            threadID,
-            threadMessageInfo[threadID],
-          ),
-        );
-      }
-      if (dbThreadMessageInfos.length === 0) {
-        return undefined;
+      if (messageStoreOperation.type === 'replace_threads') {
+        const threadMessageInfo: MessageStoreThreads =
+          messageStoreOperation.payload.threads;
+        const dbThreadMessageInfos: ClientDBThreadMessageInfo[] = [];
+        for (const threadID in threadMessageInfo) {
+          dbThreadMessageInfos.push(
+            translateThreadMessageInfoToClientDBThreadMessageInfo(
+              threadID,
+              threadMessageInfo[threadID],
+            ),
+          );
+        }
+        if (dbThreadMessageInfos.length === 0) {
+          return undefined;
+        }
+        return {
+          type: 'replace_threads',
+          payload: {
+            threads: dbThreadMessageInfos,
+          },
+        };
       }
-      return {
-        type: 'replace_threads',
-        payload: {
-          threads: dbThreadMessageInfos,
-        },
-      };
+      return messageStoreOperation;
     });
     return convertedOperations.filter(Boolean);
   },