SOLVED: some of required entries in cron_task_runs were missing.
List:
process_service_changes for all companies
backups_sftp for company 0
backups_amazons3 for company 0
license_validation for company 0
SQL commands.
For process_service_changes. Note (use your own company ids):
INSERT INTO `blesta`.`cron_task_runs` (`id`, `task_id`, `company_id`, `time`, `interval`, `enabled`, `date_enabled`) VALUES (NULL, '29', '2', NULL, '5', '1', NOW());
INSERT INTO `blesta`.`cron_task_runs` (`id`, `task_id`, `company_id`, `time`, `interval`, `enabled`, `date_enabled`) VALUES (NULL, '29', '3', NULL, '5', '1', NOW());
For other tasks:
INSERT INTO `blesta`.`cron_task_runs` (`id`, `task_id`, `company_id`, `time`, `interval`, `enabled`, `date_enabled`) VALUES (NULL, '9', '0', NULL, '5', '1', NOW());
INSERT INTO `blesta`.`cron_task_runs` (`id`, `task_id`, `company_id`, `time`, `interval`, `enabled`, `date_enabled`) VALUES (NULL, '14', '0', NULL, '5', '1', NOW());
INSERT INTO `blesta`.`cron_task_runs` (`id`, `task_id`, `company_id`, `time`, `interval`, `enabled`, `date_enabled`) VALUES (NULL, '17', '0', NULL, '5', '1', NOW());