Review Reminder Sent Error | WordPress.org

Hello,

I am looking at the stats on the page wp-admin/admin.php?page=cr-reviews-reminders&tab=sent&status=rmd_error

Sent Review Reminders -> Sent -> Error

A lot of my review reminders have the status “Error” . Can we get more details on why they errored?
I want to debug it but I don’t know how. My WordPress instance is setup properly and other plugins (or WordPress itself) can properly send emails.
Some Cusrev emails reach their destination, but almost half don’t and I want to know why.

Thanks.