Cause 1 – Ordering of xfeepro is not correct
Xfeepro is an order total module. Opencart calculate fee/cost of the order total module based on their ordering defined in Admin ->Extensions -> Order Totals. Ordering number of the xfeepro should be in between Sub-Total and Total for appearing correctly.
Cause 2: Custom checkout module
Xfeepro has been tested with quick checkout, one page checkout module. However, it might not work due to custom works or other checkout module. This issue can not be solved without checking. It might be needed ftp or store admin login to resolve. Please contact at firstname.lastname@example.org for free support.