Hello, have had this issue for a while I assume. But in any case, we have a Cisco ASR 1002 on the edge that does our routing and NAT, behind that we have a Cisco ASA 5585-X and then our LAN.
Trying ping 18.104.22.168 fails from my desktop behind the firewall, although I see the flow being created in the log for the ICMP packet. I also see the NAT translation on the edge router happening using show ip nat trans | inc 22.214.171.124.
I can however ping this IP from the edge router and the firewall.
I am attaching a doc that explains it better. You can also normally ping this IP from any other location, ex my cell phone.