Prepacking crashing using metalloprotein

Good evening, 

I'm trying to run an ensemble protein-protein docking to a protein containing a metal cluster (2Fe2S). I was able to generate ensembles for both structures, but at the Prepcking stage the application just crash. Here is the command:

$ docking_prepack_protocol.default.linuxgccrelease -in:file:s ../input/mnt_bcl2_relaxed.pdb -ensemble1 ../ensemble/mnt/mnt_A_ensemblelist -ensemble2 ../ensemble/bcl2/bcl2_B_ensemblelist -partners A_B -in:auto_setup_metals true @prepack_flag

Here is the error message:

terminate called after throwing an instance of 'std::out_of_range'

  what():  map::at

Does anyone have any idea how to solve this issue? Or what can I do to avoid this error message?