So I have been looking for a solution.
In the admin there seems te be a bug. In the file html-order-fee.php on line 59 this is the code
<?php if ( isset( $item['line_total'] ) ) echo wc_price( wc_round_tax_total( $item['line_tax'] ) );
I think this should be
<?php if ( isset( $item['line_total'] ) ) echo wc_price( wc_round_tax_total( $item['line_total'] ) );
The problem with the tax stays