Check the crond service is up and running. Please also try restarting the service:
Please check whether your cron jobs are functioning well at the OS level
---- Crontab :
20 17 * * * date >> /home/oracle/date.log
Because I have had issues, where the cron jobs fail even though the services were up and running.
Instead of redirecting everything to /dev/null, redirect to a log file.
And be aware that scripts invoked from cron do NOT inherit any environment variables, as they do when executed from a command line.
Add this to your script:
env | sort
along with the redirection of both errout and stdout to a log file, and compare the results of cron-invoked vs. command line invoked.