All store configuration is properly setup, the cron is running, everything else is working, but there are no catalog_product_alert schedule entries being generated or back in stock alerts sent.
I have only found one curiosity, the core_config_data table includes the following setting:
crontab/default/jobs/catalog_product_alert/run/model : NULL
I suspect there should be some value there, but i cant seem to find any clues to what that value could be and i suspect this is part of the issue that no cron schedule is being created.
The following link helped understanding the issue, but provided no solution so far: https://community.magento.com/t5/Magento-2-x-Technical-Issues/Product-Stock-Alerts-Not-Sending/td-p/43032