Divert Unencrypted Traffic through an IPS with Local Traffic Manager

I've tried for hours to get this config setup in my lab with no luck yet. One basic problem I have (that I've verified thru tcpdumps) is this: the "main" F5 sends an arp request asking who has the IP of my backend web server ("tell 192.168.106.254", the self-IP on the inside_VG), the "IPS" F5 passes this ARP along, the backend web server receives the ARP and then sends an ARP reply. However, this ARP reply never makes it back anywhere. It's not seen by the "IPS" F5, or the "main" F5. I have this environment setup entirely on ESX, using 2 BIG-IPs and an Ubuntu web server. I have a feeling the virtual networking setup could be incorrect. Could someone who has this working describe or provide a screenshot of their virtual networking setup (ESX or Workstation) please? Thanks in advance for any help