Gmail sometimes files a group's own emails as spam, which is common for a newly used sending subdomain. Those messages were being imported straight into the junk folder, so they never appeared in the committee inbox, yet the digest still counted them and emailed you about new messages you could not find. Genuine messages from your own group addresses are now rescued into the inbox instead, anything wrongly junked before this change moves itself back on the next check, and the digest no longer counts junk, so the number you are told matches what you see.