Bethesda is hoping a release a Shivering Isles patch next Monday that will resolve the Form ID bug present in the expansion.
The bug was linked to object IDs and caused newly created objects in the game world to disappear.
A beta patch addressing this issue for PC has already been released, but what Bethesda hopes to release Monday is the full-fat version, for both PC and Xbox 360.
A Bethesda community manager described Monday as the developer's "target date" in a post on official forums. "...so hopefully all will go well in preparation for uploading these", they said.