Multipath "Leaking"

I implemented a fail over for our Metro Ethernet connection between offices using the following article:

https://community.sophos.com/products/unified-threat-management/f/hardware-installation-up2date-licensing/80484/how-to-do-backup-vpn-with-sophos-utm-9-x-more-detailed-than-kb-118975

I would like Internet IPv4 type traffic to also go over the Metro Ethernet connection and out of the other office's ISP connection should one of the office's ISP connections fail.    I have the following Multipath Rule in place  (It is toggled off right now because of the issues described below):

It appears to work at first glance but I'm having a bad side effect.  When the Metro E connection is up Internet connections are hit and miss.  Pages load every other refresh.  I toggle off the Metro E interface and all works beautifully.   I have watched the Flow Monitor for the Metro E interface while it was up and I can see TCP/80 and 443 traffic to websites like facebook and outlook.com trying to go over the Metro E when it should be trying to go out of the ISP interface first.   I've messed around with different weights and persistence timeouts but nothing has corrected this behavior yet.  This is what is currently in both firewalls:

Any suggestions?  Thanks!