Issues with email routing from Cox to domain that was formerly hosted with Cox

My client switched providers a few months back and ever since then, their contacts that still use Cox services are unable to send or receive email from them.  Services were moved from Cox to Google GSuite to prevent the need of moving email service if they found they did not like their new carrier.

All other senders from the internet at large are able to deliver emails to the same domain at the new MX record, only senders on Cox are unable to send to us from what I can gather.  The sender doesn't appear to be receiving any bounced email message from reports.  

I called in to open a ticket and got bounced around a few times and then told some unusual statement that Cox is having issues delivering mail to Gmail.  I asked the lady on the phone if this issue has been going on for nearly 4 months, and she noncommittally stated it could have been going on longer.  I find that hard to believe, so I'm hoping this post will actually reach someone with some insight into the email and DNS servers on the Cox network.  

The domain that was migrated away from Cox is brsoccer.org.  Current, correct  MX record is: aspmx.l.google.com