ONIX 3.0 Monograph Export in OMP

Hi,
Why is it only possible to export one monograph at a time via ONIX 3.0 Monograph Export. The system is set up so that you can select all monographs at once, but the plugin will in any case generate an xml file containing data from just a single monograph.
The current OMP version is 3.1.2.1
Best
Niels Erik