Cron not running command, what's wrong?

Question

ubuntu

ubuntu 18.04
There is a cron job in /etc/crontab and it won't run:

20 * * * *      root    /usr/bin/find /home/user/temps/ -type f -mmin +20 -delete

If you run /usr/bin/find /home/user/temps/ -type f -mmin +20 -delete in the terminal - everything is fine.
grep CRON /var/log/syslog does not find that the command was executed.
journalctl -u cron.service is empty, a couple of entries from last year.
What is wrong with cron and how can I diagnose the problem more?
PS cleaned journalctl, data appeared, here's what happens in cron (but files are not deleted)

CRON[17590]: pam_unix(cron:session): session opened for user root by (uid=0)
CRON[17591]: (root) CMD (/usr/bin/find /home/user/temps/ -type f -mmin +15 -delete )
CRON[17590]: pam_unix(cron:session): session closed for user root

Added > /tmp/output- the file is empty

Answer 1

Weird!
Are you sure that there are "old" files left?
Change temporarily to something like
* * * * * root /usr/bin/find /home/user/temps >> /tmp/cron-debug.out 2>&1