Hi Yvonne,
Please check what order statuses are set to be counted in WooCommerce > Settings > Maximum Products per User > Order statuses. By default, it’s set to Completed orders only. Also don’t forget to Recalculate sales data after changing the Order statuses option.
If that is not the case – there is Editable sales data option in WooCommerce > Settings > Maximum Products per User > Admin. If you enable it and then go to some user’s profile page (i.e. in Users menu), you will be able to see which products did this user buy – that may help to understand what’s going on.