If you click into the invoices in your customer page reports, you will sometimes see more invoice line items than should be included in the your calculation of, for example, MRR.

If we use INV-0325 as an example and click in to view the invoice.

You can see the annual subscription amount of £12,000 and a professional services fee of £3,000. These are all services billed in relation to the invoice. 

Only amounts included in the filters are shown in the report summary and customer summary.

This is reflected in the £1,000 per month value of MRR in the report.