Hello,
As per the above logs the packet is getting dropped on the ISG side of the tunnel with the error "packet dropped, no way(tunnel) out".
Please refer the below KB article to resolve the issues related to the above error.
http://kb.juniper.net/InfoCenter/index?page=content&id=KB7253&actp=search
As per the above KB article if you have multiple tunnels on the same tunnel interface then this issue can happen but as you have specified in your earlier posts that there is no other tunnel binded to this interface, hence i suppose that multiple phase 2 on the ISG side is causing the issue.
Please try and clear the IKE and IPSEC association (phase 1 and phase 2) from ISG and SRX both if possible or atleast from one side and then check if it resolves the issue.
Thanks,
Pulkit Bhandari
Please mark my response as Solution Accepted if it Helps, Kudos are Appreciated too. 