Hello @anphira,
Sorry for the inconvenience caused.
After debugging the issue, it was found that some database tables of the plugins are not created correctly due to some reasons.
To fix this issue I have enabled the Delete plugin data option from plugin settings and deleted the plugin.
Basically, this option deletes all tables and options created by the plugin once you delete the plugin.
Then I reinstalled the plugin and confirmed the working and it is working fine. Both issues which are emails not scheduling and some options not saving are fixed.
Please see here:
https://share.bsf.io/BluWZ1AW
https://share.bsf.io/jkuWlDkw
Now to fix the same on your live site you have two ways.
The first one is to enable the Delete plugin data option as I explained above. Not note that all recoverable order and recovered order data will be lost. Also if you have customized the plugin email templates then they are not available. The default template will be restored.
The second one is to delete the cartflows_ca_email_templates_meta table from the database and re-create it. Here you will lose the email template settings but after recreating it will work fine. If you are going with this option then please connect to your host to do this for you as there might be changes to the error on your site.
While creating the database table you can take the same table reference from the staging site as it is created correctly.
If your host required any details regarding the above database table then let us know.
Hope this helps.