Symptoms

Subscription Expiration Date is changed manually. After this change this subscription is not generating BO (Billing Order).

Cause

Subscription is rated by Rating Engine. Manually changing subscription expiration date is not supported by Rating Engine. Due to the fact that the subscription was not renewed properly, renewal notches were not generated, so such subscription is considered expired. 

Resolution

Move the subscription expiration date back, place a renewal order and avoid changing expiration date manually in the future.

Also, there is a Feature Request with ID #PFR-6402 to Remove ability to change NBD / Expiration Date on subscription rated by new RE.