That's been a huge problems for a long time. The BS answer I got is clients fall off when they do updates. To get your hard earned comms, you've got to drill through RPP & your comm statement then put it all in their Excel form to get reconnected to your customers - which only partially works.
PS: People do fall off - leave the state, get married, new job etc. - best to contact the missing people to see if they really did leave - or are still insured & paid to date.