Hi Tang,
How much memory do you have allocated for the batchserver VM? With 8 vCPUs, you will run 8 copies of the batch workload in parallel and then run 2 copies in parallel. In the .debug log, for the first run, I am seeing errors of the form "Error mallocing memory" and 5 of the 8 copies of the workload terminated after 9 seconds (vs. the expected ~45 sec run on the other 3). The second run of 2 copies completed fine, which is why there was no debug file for it.
There are 2 ways to address this: add more memory to the VM or reduce the number of vCPUs to 3 or fewer. For most publications, 1 or 2 vCPUs are used for the batchserver configuration, so I would recommend this approach. The requirement for the batch server is that all 10 copies of the workload completes in less than 900 seconds, so even with 1 vCPU you should be fine.