diff --git a/addons/web/static/src/model/relational_model/relational_model.js b/addons/web/static/src/model/relational_model/relational_model.js
index 707b7c999a2..9f411d7fb1f 100644
--- a/addons/web/static/src/model/relational_model/relational_model.js
+++ b/addons/web/static/src/model/relational_model/relational_model.js
@@ -410,7 +410,7 @@ export class RelationalModel extends Model {
                 groupData[config.groupBy[0]],
                 group.range
             );
-            group.rawValue = groupData[config.groupBy];
+            group.rawValue = groupData[config.groupBy[0]];
             group.displayName = getDisplayNameFromGroupData(
                 groupByField,
                 groupData[config.groupBy[0]]
@@ -429,6 +429,10 @@ export class RelationalModel extends Model {
                         groupBy,
                     },
                 };
+                if (isRelational(config.fields[firstGroupByName]) && !group.value) {
+                    // fold the "unset" group by default when grouped by many2one
+                    config.groups[group.value].isFolded = true;
+                }
                 if (groupRecordConfig) {
                     config.groups[group.value].record = {
                         ...groupRecordConfig,
@@ -464,9 +468,6 @@ export class RelationalModel extends Model {
             } else {
                 group.records = [];
             }
-            if (isRelational(config.fields[firstGroupByName]) && !group.value) {
-                groupConfig.isFolded = true;
-            }
             if (!groupConfig.isFolded) {
                 nbOpenGroups++;
                 if (nbOpenGroups > this.constructor.MAX_NUMBER_OPENED_GROUPS) {
diff --git a/addons/web/static/tests/views/kanban/kanban_view_tests.js b/addons/web/static/tests/views/kanban/kanban_view_tests.js
index bd45555b186..bb9b6eecea6 100644
--- a/addons/web/static/tests/views/kanban/kanban_view_tests.js
+++ b/addons/web/static/tests/views/kanban/kanban_view_tests.js
@@ -1738,6 +1738,50 @@ QUnit.module("Views", (hooks) => {
         assert.containsN(target, ".thisisdeletable", 4, "records should be deletable");
     });
 
+    QUnit.test("kanban grouped by many2one: false column is folded by default", async (assert) => {
+        serverData.models.partner.records[0].product_id = false;
+
+        const kanban = await makeView({
+            type: "kanban",
+            resModel: "partner",
+            serverData,
+            arch: `
+                <kanban>
+                    <templates>
+                        <t t-name="kanban-box">
+                            <div><field name="foo"/></div>
+                        </t>
+                    </templates>
+                </kanban>`,
+            groupBy: ["product_id"],
+        });
+
+        assert.containsN(target, ".o_kanban_group", 3);
+        assert.containsOnce(target, ".o_column_folded");
+        assert.deepEqual(getNodesTextContent(target.querySelectorAll(".o_kanban_header")), [
+            "None1",
+            "hello",
+            "xmo",
+        ]);
+
+        await click(target.querySelector(".o_kanban_header"));
+        assert.containsNone(target, ".o_column_folded");
+        assert.deepEqual(getNodesTextContent(target.querySelectorAll(".o_kanban_header")), [
+            "None",
+            "hello",
+            "xmo",
+        ]);
+
+        // reload -> None column should remain open
+        await reload(kanban, { groupBy: ["product_id"] });
+        assert.containsNone(target, ".o_column_folded");
+        assert.deepEqual(getNodesTextContent(target.querySelectorAll(".o_kanban_header")), [
+            "None",
+            "hello",
+            "xmo",
+        ]);
+    });
+
     QUnit.test("quick created records in grouped kanban are on displayed top", async (assert) => {
         await makeView({
             type: "kanban",