Unflattening may not always be possible. Here are examples of such cases:
- GoodReader's Unflattening only works if GoodReader previously flattened the file. GoodReader can't reverse flattening performed by other apps.
- Any editing - annotating or page editing - of previously flattened PDF file permanently kills the possibility of further unflattening.
- The file may have been flattened with the "Unflattening is allowed" switch in Settings set to OFF.