Some more poking around is needed ..
When you run the main cron successfully, the end will say this:
Ran 0 adhoc tasks found at Wed, 31 Mar 2021 10:49:49 -0500
Cron script completed correctly
Cron completed at 10:49:49. Memory used 33.2MB.
Execution took 0.557945 seconds
It's not that Moodle never tries to run autobackup, but rather, jobs that don't complete for some reason get recorded in adhoc_task to pick up where it left off when it didn't complete.
Since you have terminal ...
cd /path/to/moodlecode/admin/tool/task/cli/ (note that's command line)
in there: schedule_task.php
Help on that ... /path/to/correct/php schedule_task.php
Add --list List all scheduled tasks
php schedule_task.php --list |grep automated_backup_task
above searches for automated_backup_task
will show something like:
\core\task\automated_backup_task 50 * * * * * Wednesday, 31 March 2021, 9:50 AM Wednesday, 31 March 2021, 10:50 AM
Warning; if your autobackups have been stuck, running anything that forces autobackups might be pretty intensive and take a long time.
But, one has to get it to finish ... I've had to use 'nohup' (no hang up) command in front of the php command execution and an & at end to put a stuck thang executing in the background until completed. Doing that made server slow but ....
nohup php [command with options] &
That puts the command in background and logs to a file at location and allows you to escape from that command in the shell. Otherwise, one would have to leave that ssh session open and running to finish.