'Record'- File missing

Hi All,

I have a bash script that originate bulk calls (max concurrent 20 call) using AMI.
Each call when answered, is asked to record the b-leg for 5 minutes, but some of the calls just does not get recorded and Asterisk doesn’t log any warning/error, while most of them are being recorded.

Any one having idea what could be the issue?
My Asterisk version is : Asterisk 1.8.15-cert4