For those who face CRON stopping without logged error, just a little hint.
In most cases, it comes from reached timeout.

The first important parameter is PHP execution_max_time
Projeqtor tries to refresh this value with set_time_limit() function.
But this function may be disabled on your PHP stack.

More frequently, this issue may occure when using PHP-fpm.
In this deployment of PHP, it is not integrated as a module in Apache.
This is default configuration when using NGINX as web server.
Then you'll have to change the resuest_slowlog_timeout, as this will stop the script to write a trace.
Possibly also change request_terminate_timeout.
Here is a proposale to change in /etc/php/7.x/fpm/pool.d/www.conf

;request_terminate_timeout = 60s
;request_slowlog_timeout = 10s
request_terminate_timeout = 0
request_slowlog_timeout = 0