Extract only processes first page after successful pack

[posbios]

On a first basic test, packing works correctly, but extraction only processes the first page.

Steps to reproduce:

Pack a multi-page input.

Run extract on the generated output.

Expected behavior:
All pages should be extracted.

Actual behavior:
Only the first page is extracted.

Notes:
This happens on the very first simple try, no edge cases or advanced options involved.

[ef1500]

You have to set --asset=-1 for the extraction to work properly. Let me know if that works.