Currently, prims owned by the script owner aren't able to be returned as per the wiki:
"As a security measure, parcel owner, estate owner, and estate managers can not have their objects returned by this method, except when the object returns itself."
...which is understandable for user-rezzed content.
Please update llReturnObjectsByID() with a check to allow return of self-rezzed objects.
These are objects rezzed by the same object calling llReturnObjectsByID().
Whenever I have a massive amount of content that I wish to update in an automated fashion, I can't complete the process without tedious, repetitive, manual intervention come time to return each object to my inventory.
This update would allow the process to be completely automated.