diff --git a/addons/mail/static/src/core/common/message_reactions_model.js b/addons/mail/static/src/core/common/message_reactions_model.js
index 4110fc7331e..7ab774dd964 100644
--- a/addons/mail/static/src/core/common/message_reactions_model.js
+++ b/addons/mail/static/src/core/common/message_reactions_model.js
@@ -13,9 +13,10 @@ export class MessageReactions extends Record {
      * @returns {import("models").MessageReactions}
      */
     static insert(data) {
-        let reaction = this.store.Message.get(data.message.id)?.reactions.find(
-            ({ content }) => content === data.content
-        );
+        if (data.message && !(data.message instanceof Record)) {
+            data.message = this.store.Message.insert(data.message);
+        }
+        let reaction = data.message.reactions.find(({ content }) => content === data.content);
         if (!reaction) {
             /** @type {import("models").MessageReactions} */
             reaction = this.preinsert(data);
@@ -46,7 +47,7 @@ export class MessageReactions extends Record {
             count: data.count,
             content: data.content,
             message: data.message,
-            personas: reaction.personas.filter((p) => !personasToUnlink.has(p)),
+            personas: reaction.personas.filter((p) => !personasToUnlink.has(p.localId)),
         });
         return reaction;
     }
diff --git a/addons/mail/static/tests/helpers/mock_server/models/mail_message.js b/addons/mail/static/tests/helpers/mock_server/models/mail_message.js
index 11bf3b576ad..65eb1a299ec 100644
--- a/addons/mail/static/tests/helpers/mock_server/models/mail_message.js
+++ b/addons/mail/static/tests/helpers/mock_server/models/mail_message.js
@@ -78,7 +78,10 @@ patch(MockServer.prototype, {
                         guests: [],
                         message: { id: messageId },
                         partners: [
-                            ["ADD", { id: this.pyEnv.currentPartnerId, name: currentPartner.name }],
+                            [
+                                action === "add" ? "ADD" : "DELETE",
+                                { id: this.pyEnv.currentPartnerId, name: currentPartner.name },
+                            ],
                         ],
                     },
                 ],
diff --git a/addons/mail/static/tests/message/message_tests.js b/addons/mail/static/tests/message/message_tests.js
index e9ec4f7f4ba..17d1c32e481 100644
--- a/addons/mail/static/tests/message/message_tests.js
+++ b/addons/mail/static/tests/message/message_tests.js
@@ -531,6 +531,8 @@ QUnit.test("Two users reacting with the same emoji", async () => {
     await contains(".o-mail-MessageReaction", { text: "😅2" });
     await click(".o-mail-MessageReaction");
     await contains(".o-mail-MessageReaction", { text: "😅1" });
+    await click(".o-mail-MessageReaction");
+    await contains(".o-mail-MessageReaction", { text: "😅2" });
 });
 
 QUnit.test("Reaction summary", async () => {