diff --git a/addons/project/models/project_task.py b/addons/project/models/project_task.py
index d3cbc192103..c27346b8fa9 100644
--- a/addons/project/models/project_task.py
+++ b/addons/project/models/project_task.py
@@ -553,6 +553,7 @@ class Task(models.Model):
         if self._origin:
             # fetch 'user_ids' in superuser mode (and override value in cache
             # browse is useful to avoid miscache because of the newIds contained in self
+            self.invalidate_recordset(fnames=['user_ids'])
             self._origin.fetch(['user_ids'])
         for task in self.with_context(prefetch_fields=False):
             task.portal_user_names = ', '.join(task.user_ids.mapped('name'))