Hi @Jan_Hetherington, thanks for reaching out! Could you try checking if the tasks are under the Unscheduled section when you open the calendar week view?
If you still cannot find the tasks, I recommend you reaching out to our support team and share the URL of one of the tasks that you see in Month view but not in Week view. They will be able to identify what is causing this issue: How to contact our Support Team ✉. I hope this helps!