This article provides the mitigation step for the issue where security traceoptions file is configured to capture traffic but there is no data getting recorded in the file.

There could be an instance where security traceoptions file has been configured to capture the trace logs for a traffic but post running the traffic test, the traceoptions file remains empty and of size 0.

Although, the flow session is getting created on the SRX and flow statistics are also increasing like packets/bytes but still if this behaviour is observed then to mitigate this, try restarting the network security trace daemon (nstraced) using command 'restart network-security-trace'.
 

Post configuration of the packet capture for high end, on starting the datapath-debug if you get " network-security-trace subsystem is not responding to management requests " please try restarting the network security trace daemon (nstraced) using command 'restart network-security-trace'.
 
root@SRX> request security datapath-debug capture start
network-security-trace subsystem is not responding to management requests
 
root@SRX> restart network-security-trace ?
Possible completions:
 <[Enter]>      Execute this command
 gracefully      Gracefully restart the process
 immediately     Immediately restart (SIGKILL) the process
 soft         Soft reset (SIGHUP) the process
 |          Pipe through a command
root@SRX> restart network-security-trace
Network security trace daemon started, pid 62248
root@SRX>
 

If the restart of network security trace daemon doesn't resolves the issue, try rebooting the firewall.