FCPX crashes when importing MXF

hi,

the footage i'm trying to import comes from SONY PXW-X70, which gave me MXF files.

those files can be read by VLC, no problem, there's something in there!

but as soon as i start importing them in fcpx, it crashes

i tried to import a different kind of footage and it worked well

it's a brand new imac 27 16go ram, updated, pro video codecs included

rebooted the computer, re-installed fcpx already

i usually have no problems but footage use to come from alexa cam

i thought fcpx could ingest MXF files without having to transcode it.

if you have any idea...

thanks,

ercorr