We recently saw the first release of Apache OpenOffice, one of the branches of the OpenOffice.org fork. Since the tangled mess usually known as the Open Document Format (ODF) was initially based on the OpenOffice.org file format, one could reasonably expect that Apache OpenOffice and LibreOffice are both quite successful in implementing that file format. Especially since Apache OpenOffice was according to the initial OpenOffice.org Apache incubator proposal intended to
serve as a reference implementation of the Open Document Format standard
one should have expected an attempt to provide a correct ODF 1.2 implementation.
In 2009, a bug was filed against OpenOffice.org. That bug report was later moved to Apache OpenOffice and duplicated to LibreOffice. Essentially this bug is related to how errors return by OpenFormula formulas are saved inside the ODF file. It should have been relatively easy to fix this bug. Unfortunately the recent Apache OpenOffice release shill exhibits the faulty behaviour. As a consequence other implementations that endeavour to provide interoperability still have to work around this bug.
It has abundantly clear to me that both Apache OpenOffice and LibreOffice at most provide lip service with regard to interoperability.