If one of your crontab entries is not running lately without any errors, check if you have a newline at the end of the crontab, because if you do not, then the last job will never be executed and no error will be reported anywhere: 79037 (and possibly cause of 260789)

Oh and it will also not run /etc/cron.d/ file with a "." in the name: 324922

I managed to hit both of these bugs within a single day, yay me :P