Not creating site backups

Hi.
I've migratied my ISPConfig to a new server. On the new one I'm unable to produce site backups from ISPConfig.
I've ajusted the path in System > Server configuration > Backup directory which is owned by root:root, permissions 755, parent 750. In config I've set up backups at night, in site config but in the morning I find nothing in the destination path.
I checked cron.log and ispconfig.log but couldn't find any error or warning. In the site Backup tab I see some backups generated on the old server, but if I press Delete backup nothing happens.
What can I do to debug sites backups?
Thanks

EDIT: manually running cron_debug generates backups! (suggested here)

 

I have no running tasks in cron table. But why does it says next run in 2020?

Code:

MariaDB [dbispconfig]> select * from sys_cron;
+-----------------------------------+---------------------+---------------------+---------+
| name                              | last_run            | next_run            | running |
+-----------------------------------+---------------------+---------------------+---------+
| cronjob_mailbox_stats             | 2019-08-14 00:00:01 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_clamav_log        | 2019-08-13 12:56:01 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_cpu               | 2019-08-13 12:56:01 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_database_size     | 2019-08-13 12:56:01 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_disk_usage        | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_email_quota       | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_fail2ban          | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_hd_quota          | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_iptables          | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_ispconfig_log     | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_ispconfig_version | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_mail_log          | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_mail_queue        | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_mem_usage         | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_openvz            | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_os_version        | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_raid              | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_rkhunter          | 2019-08-14 00:00:01 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_server            | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_services          | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_syslog            | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_monitor_system_update     | 2019-08-13 12:56:02 | 2020-01-01 00:00:00 |       0 |
| cronjob_awstats                   | 2019-08-14 00:03:43 | 2020-01-01 00:00:00 |       0 |
| cronjob_webalizer                 | 2019-08-14 00:07:57 | 2020-01-01 00:00:00 |       0 |
| cronjob_ftplogfiles               | 2019-08-14 00:07:57 | 2020-01-01 00:00:00 |       0 |
| cronjob_logfiles                  | 2019-08-14 00:07:57 | 2020-01-01 00:00:00 |       0 |
| cronjob_quota_notify              | 2019-08-14 00:07:58 | 2020-01-01 00:00:00 |       0 |
| cronjob_openvz                    | 2019-08-14 00:07:58 | 2020-01-01 00:00:00 |       0 |
| cronjob_backup                    | 2019-08-14 00:30:01 | 2020-01-01 00:30:00 |       0 |
| cronjob_backup_mail               | 2019-08-14 00:07:58 | 2020-01-01 00:00:00 |       0 |

 

Backup working after applying the patch at #5369, thanks!