I have the same problem in one of my plugin :/
I wasn’t sure if the cron function will be called directly or by CURL so I changed the hlex_cronjob() to see if it’s called:
function hlex_cronjob() {
update_option('hlex_test', now());
}
Now i’m sure that is not called because I can see in wp_options that the row hlex_test is not updated.
So i still can’t find a solutions :/