Copy commerce_abandoned_carts_email.tpl.php to your theme directory (tried with Bartik, Bootstrap and Basic), tried root dir of the theme or templates/ dir, etc.
Edit the copied commerce_abandoned_carts_email.tpl.php e.g. remove site logo or add any basic HTML/text.
Flush caches.
Create an order and run cron.
Email is delivered with default commerce_abandoned_carts_email.tpl.php from module's directory, because none of the changes from theme directory are not applied.
There's also a typo in the settings under 'Send BCC?' it says 'monintoring'.