When an order is placed, the "title" of the shipping method that is added to the order and orter_total tables is taken from the language file in the front-end, either "text_title" or "text_description" (Fedex, Flat Rate, Item Based and Pickup use the "text_description", the others use the "text_title").
Since, the full report module is an administrative module, it makes use of the language files in the back-end. The query to calculate shipping by shipping methods uses the "heading_title" from the (admin) language file as a search parameter (eg. select all from the order_total table where the title equals the "heading_title" from the language file). The bug exists where the "heading_title" in the admin language file is different to the "text_title" or "text_description" in the front-end language file. Example: the front-end language file for the ups has a "text_title" of "United Parcel Service", while the admin language file has a "heading_title" of "UPS". Subsequently, the order records a shipping method of "United Parcel Service", while the query for the report is looking for "UPS".
The following shipping methods will cause problems as a result: