Success, with minor change in syntax I am now able to send schedule mail using Cron jobs to kick off schedule mails. Here is my method for running CiviCRM cron jobs on Bluehost shared hosting every 16 minutes. Previously I had also specified the the parameter job.execute, which I have removed.
wget -O - -q -t 1 'https://<my-domain>/wp-content/plugins/...
Welcome to SE! If it were working when you use 'Execute now' but not from cron, then I'd look at the cron settings. But in your case 'Execute now' is not producing mails and that does not involve cron.
=== edited ===
Are you using Mosaico and Flexmailer - if so, which versions?
What are your settings for outbound mail?
At the place where you add recipient ...