diff --git a/addons/im_livechat/static/src/models/discuss_sidebar_category.js b/addons/im_livechat/static/src/models/discuss_sidebar_category.js
index efaa41556c4..92b20c7a45e 100644
--- a/addons/im_livechat/static/src/models/discuss_sidebar_category.js
+++ b/addons/im_livechat/static/src/models/discuss_sidebar_category.js
@@ -14,6 +14,14 @@ addFields('DiscussSidebarCategory', {
 });
 
 patchFields('DiscussSidebarCategory', {
+    categoryItemsOrderedByLastAction: {
+        compute() {
+            if (this.discussAsLivechat) {
+                return this.categoryItems;
+            }
+            return this._super();
+        },
+    },
     isServerOpen: {
         compute() {
             // there is no server state for non-users (guests)
@@ -37,18 +45,18 @@ patchFields('DiscussSidebarCategory', {
             return this._super();
         },
     },
-    serverStateKey: {
+    orderedCategoryItems: {
         compute() {
             if (this.discussAsLivechat) {
-                return 'is_discuss_sidebar_category_livechat_open';
+                return this.categoryItemsOrderedByLastAction;
             }
             return this._super();
         },
     },
-    sortComputeMethod: {
+    serverStateKey: {
         compute() {
             if (this.discussAsLivechat) {
-                return 'last_action';
+                return 'is_discuss_sidebar_category_livechat_open';
             }
             return this._super();
         },
diff --git a/addons/mail/static/src/models/discuss_sidebar_category.js b/addons/mail/static/src/models/discuss_sidebar_category.js
index 8542271cf95..82976a5c92b 100644
--- a/addons/mail/static/src/models/discuss_sidebar_category.js
+++ b/addons/mail/static/src/models/discuss_sidebar_category.js
@@ -168,6 +168,49 @@ registerModel({
             },
             default: '',
         }),
+        /**
+         * Determines the discuss sidebar category items that are displayed by
+         * this discuss sidebar category.
+         */
+        categoryItems: many('DiscussSidebarCategoryItem', {
+            inverse: 'category',
+        }),
+        categoryItemsOrderedByLastAction: many('DiscussSidebarCategoryItem', {
+            compute() {
+                if (this.discussAsChat) {
+                    return this.categoryItems;
+                }
+                // clear if the value is not going to be used, so that it avoids
+                // sorting the items for nothing
+                return clear();
+            },
+            sort() {
+                return [
+                    ['truthy-first', 'thread'],
+                    ['truthy-first', 'thread.lastInterestDateTime'],
+                    ['most-recent-first', 'thread.lastInterestDateTime'],
+                    ['greater-first', 'channel.id'],
+                ];
+            },
+        }),
+        categoryItemsOrderedByName: many('DiscussSidebarCategoryItem', {
+            compute() {
+                if (this.discussAsChannel) {
+                    return this.categoryItems;
+                }
+                // clear if the value is not going to be used, so that it avoids
+                // sorting the items for nothing
+                return clear();
+            },
+            sort() {
+                return [
+                    ['truthy-first', 'thread'],
+                    ['truthy-first', 'thread.displayName'],
+                    ['case-insensitive-asc', 'thread.displayName'],
+                    ['smaller-first', 'channel.id'],
+                ];
+            },
+        }),
         /**
          * The title text in UI for command `add`
          */
@@ -183,31 +226,6 @@ registerModel({
             },
             default: '',
         }),
-        /**
-         * Determines the discuss sidebar category items that are displayed by
-         * this discuss sidebar category.
-         */
-        categoryItems: many('DiscussSidebarCategoryItem', {
-            inverse: 'category',
-            sort() {
-                switch (this.sortComputeMethod) {
-                    case 'name':
-                        return [
-                            ['truthy-first', 'thread'],
-                            ['truthy-first', 'thread.displayName'],
-                            ['case-insensitive-asc', 'thread.displayName'],
-                            ['smaller-first', 'channel.id'],
-                        ];
-                    case 'last_action':
-                        return [
-                            ['truthy-first', 'thread'],
-                            ['truthy-first', 'thread.lastInterestDateTime'],
-                            ['most-recent-first', 'thread.lastInterestDateTime'],
-                            ['greater-first', 'channel.id'],
-                        ];
-                }
-            },
-        }),
         /**
          * States the total amount of unread/action-needed threads in this
          * category.
@@ -231,7 +249,7 @@ registerModel({
          */
         filteredCategoryItems: many('DiscussSidebarCategoryItem', {
             compute() {
-                let categoryItems = this.categoryItems;
+                let categoryItems = this.orderedCategoryItems;
                 const searchValue = this.messaging.discuss.sidebarQuickSearchValue;
                 if (searchValue) {
                     const qsVal = searchValue.toLowerCase();
@@ -343,6 +361,17 @@ registerModel({
                 return clear();
             },
         }),
+        orderedCategoryItems: many('DiscussSidebarCategoryItem', {
+            compute() {
+                if (this.discussAsChannel) {
+                    return this.categoryItemsOrderedByName;
+                }
+                if (this.discussAsChat) {
+                    return this.categoryItemsOrderedByLastAction;
+                }
+                return clear();
+            },
+        }),
         /**
          * The key used in the server side for the category state
          */
@@ -357,22 +386,6 @@ registerModel({
                 return clear();
             },
         }),
-        /**
-         * Determines the sorting method of channels in this category.
-         * Must be one of: 'name', 'last_action'.
-         */
-        sortComputeMethod: attr({
-            compute() {
-                if (this.discussAsChannel) {
-                    return 'name';
-                }
-                if (this.discussAsChat) {
-                    return 'last_action';
-                }
-                return clear();
-            },
-            required: true,
-        }),
         /**
          * Channel type which is supported by the category.
          */