Enable OpenOffice conversion logging
Conversion logging gives you extended diagnostics when OpenOffice converts documents. OpenOfficeComConverter.exe.config, in C:\Program Files\ABBYY FlexiCapture 12 Stations, and add this listener.
AooConverter.log in the %temp% directory.
Reproduce the error and analyze the relevant entries. If you cannot fix it yourself, contact ABBYY technical support with the log file.