Hi!
I have similiar problem with my zen cart order status update emails.
All new orders will receive automatic order confirmation emails, but not when I edit the order status. I haven't done any modifications to those files mentioned above or email settings.

Order status update emails do work:
- when editing very old orders.
- when using super orders mod to edit orders.

This broblem seems weird and I have no idea how to fix it. I would appreciate a lot if somebody could help with this. I can still use super orders mod for this, but I would prefer using the original editor and to fix this error.

Zen cart version 1.3.9.h