Event that was received on the gateway still had SHA1 certificate signature which is of 2048 key length. As certificates were migrated to SHA2 the key length has to be 4096.
Policies used to generat the event and Automatic Action still had SHA1 signature. Due to this mismatch in signing signatures present, the Operations Agent (OA) proces opcmsgi is picking the wrong signature and is appending it to the event generated, which is wrong. So to sort out this problem had to redeploy the policies on to the agent node after the certificate migration, that would make the policies to have the new signature.
After redeploying the policies, events worked and Automatic Action information was populated in OMi event side.