Hi @RichardR and thanks for reaching out. This isn’t a bug but a current behaviour; when assigning tasks from templates to your colleagues, they will automatically show in their My Tasks. This is definitely something on our radar (and a popular request in the Forum, so if you haven’t yet, you can add your vote to: Project Template assigned tasks show up in My Tasks automatically). Until we come up with a better solution for this issue, I would recommend moving these tasks to the “Later” section of your My Tasks using the “Tab + L” shortcut.
Hope this helps, have a great weekend!