One of your scheduled job appears to not be working and you want to investigate this. Here are the initial steps to take in order to troubleshoot this issue.
Log the cron output in a log file
As explained in the documentation https://docs.acquia.com/cloud-platform/manage/cron/#scheduled-job-output we recommend you to log the cron output to a file in the server’s logs directory in order to be able to debug your job.
Look for the log file on the server
The log file saved on the server should be updated as often as the scheduled job is run. If you do see that the file gets updated as expected, it means that the job is correctly triggered at the platform level and that you need to inspect the log file itself
Analyse the log file
Once you have established that the issue is not that the job is not triggered, you need to check the log file and look for errors. Please note that in this case, adding a timestamp to the log messages will help troubleshooting the error(s).