Hi Esther,
I haven’t tried importing any of the pre-processed data. The only thing that I did was to make sure we could import the transformation matrices correctly. The only things I would be able to investigate are errors occurring during one the steps of the HCP tutorial: http://neuroimage.usc.edu/brainstorm/Tutorials/HCP-MEG
Please let me know at which step of this tutorial you are getting unexpected results, and with which subjects it occurs so I can try to reproduce the issue on my end.
Thanks
Francois