I am helping a friend with this problem... She was trying to Log and Transfer in FCP with a backup of an SD card (shot with a friend's consumer Canon camera) but had this error message in FCP.
"AVCHD" contains unsupported media or has an invalid directory structure. Please choose a folder whose directory structure matches supported media.
She's familiar with this process and was certain that she backed up the entire folder, maintaining proper file structure. I believe the directory might have been messed up by another user because they were passing the SD card around.
I was wondering if anyone can recommend a good MTS converter to convert the MTS files so that she can edit the footage in FCP. In the past, she has been using Log and Transfer, transcoding it to Apple Pro Res for editing.