diff --git a/lib/reducers/message-reducer.js b/lib/reducers/message-reducer.js
--- a/lib/reducers/message-reducer.js
+++ b/lib/reducers/message-reducer.js
@@ -1874,7 +1874,8 @@
     const sendingComposableDMMessageToPeers =
       composableMessageID &&
       outboundP2PMessages &&
-      outboundP2PMessages.length > 0;
+      outboundP2PMessages.length > 0 &&
+      action.dispatchSource !== 'tab-sync';
 
     // For composable DM messages, we rely on dedicated actions
     // (`sendTextMessageActionTypes` or `sendMultimediaMessageActionTypes`)
diff --git a/lib/shared/dm-ops/process-dm-ops.js b/lib/shared/dm-ops/process-dm-ops.js
--- a/lib/shared/dm-ops/process-dm-ops.js
+++ b/lib/shared/dm-ops/process-dm-ops.js
@@ -154,7 +154,11 @@
           messagesNotifyTypes: {},
         };
         dispatchWithMetadata(
-          { type: processDMOpsActionType, payload },
+          {
+            type: processDMOpsActionType,
+            payload,
+            dispatchSource: 'tunnelbroker',
+          },
           dispatchMetadata,
         );
 
@@ -289,7 +293,11 @@
         messagesNotifyTypes,
       };
       dispatchWithMetadata(
-        { type: processDMOpsActionType, payload },
+        {
+          type: processDMOpsActionType,
+          payload,
+          dispatchSource: 'tunnelbroker',
+        },
         dispatchMetadata,
       );
     },
@@ -404,7 +412,11 @@
         messagesNotifyTypes,
       };
       dispatchWithMetadata(
-        { type: processDMOpsActionType, payload },
+        {
+          type: processDMOpsActionType,
+          payload,
+          dispatchSource: 'tunnelbroker',
+        },
         { dmOpID },
       );
 
diff --git a/lib/types/redux-types.js b/lib/types/redux-types.js
--- a/lib/types/redux-types.js
+++ b/lib/types/redux-types.js
@@ -1563,6 +1563,7 @@
     | {
         +type: 'PROCESS_DM_OPS',
         +payload: ProcessDMOpsPayload,
+        +dispatchSource?: DispatchSource,
       }
     | {
         +type: 'INVALIDATE_TUNNELBROKER_DEVICE_TOKEN',
diff --git a/web/redux/redux-setup.js b/web/redux/redux-setup.js
--- a/web/redux/redux-setup.js
+++ b/web/redux/redux-setup.js
@@ -547,12 +547,6 @@
   }
 
   // The operations were already dispatched from the main tab
-
-  // For now the `dispatchSource` field is not included in any of the
-  // redux actions and this causes flow to throw an error.
-  // As soon as one of the actions is updated, this fix (and the corresponding
-  // one in tab-synchronization.js) can be removed.
-  // $FlowFixMe
   if (action.dispatchSource === 'tab-sync') {
     return state;
   }
diff --git a/web/redux/tab-synchronization.js b/web/redux/tab-synchronization.js
--- a/web/redux/tab-synchronization.js
+++ b/web/redux/tab-synchronization.js
@@ -9,11 +9,6 @@
 const tabSynchronizationMiddleware: Middleware<AppState, Action> =
   () => next => action => {
     const result = next(action);
-    // For now the `dispatchSource` field is not included in any of the
-    // redux actions and this causes flow to throw an error.
-    // As soon as one of the actions is updated, this fix (and the corresponding
-    // one in redux-setup.js) can be removed.
-    // $FlowFixMe
     if (action.dispatchSource === 'tunnelbroker') {
       WEB_REDUX_CHANNEL.postMessage(action);
     }