So this is the scenario:
local host - local VPN gateway - ge-0/0/0.0 -------------- interface X - remote VPN gateway - remote host
localhost IP = 192.168.1.190
remote IP = 192.168.75.5
As I explained in my previous post, on the local VPN gateway, you need a route that tells that you can reach 192.168.75.5 through the interface ge-0/0/0.0
I repeat: I believe you have such a route as you can see the counter for encrypted packets increasing. This is why the local gateway knows that the traffic sent to the zone untrust and this is we match the security policy "vpn-trust-1" that will send IP packet over the IPsec VPN "ike-vpn"
For traffic initiated on the remote gateway, the traffic hits the remote VPN gateway which then needs to route the traffic destined to 192.168.1.190.
On that remote gateway you need to run : "show route 192.168.1.190". The next-hop must be the interface X. If such a route is not present, how does the remote gateway knows how to route the traffic?
"I am pretty sure the configuration issue will be on the other side device not returning the traffic to the tunnel back to the SRX." I totally agree. This is why I asked to checked the routing on the remote gateway.
Also did you check that there is no asymmetric routing? Is the remote host sending traffic back the remote VPN gateway? and via the same incoming security zone?
Can you see the session on the remote gateway? Do you see the return traffic?
Can you run a packet capture on the remote host? Do you see the incoming ping?