Email Forwarding not functioning correctly

I've been using cPanel for a number of years now with no issues. I have numerous email forwarders set up, some of which are to gmail accounts and others are to cPanel mailboxes. Until 5:38pm on Thu 2 June these all worked fine with email being forwarded to those various places and any email that wasn't forwarded was caught by the "Default Address". I know that something happened between 5:38pm and 7:10pm by checking the "Track Delivery" via cPanel. At 7:10pm, and for all emails after that, the emails are forwarded by the email to the correct place but, in addition, the emails also make it through to the end of the process and are also sent to the "Default Address". From 7:10pm there are two copies in "Track Delivery" for nearly every email (there's only one copy if no forwarding address has been set up for that address). Has something been changed on the software? Is this intentional? Do I need to set up email forwarding in a different manner now? Does anyone recognise this problem please?