Are you sure it's on isg1000 side ? Because I've already checked all routes from isg1000 to SRX and on the logs looks like the traffic go til the last hop before the SRX and can't enter IN ?
Can you check my configuration ? maybe i did something bad in the vpn configuration or in polycies ?
Also something is strange, I have 2 SA for the Phase 2 in my VPN monitor ...