[Freesurfer] Crippled fiber tracts in healthy subjects (TRACULA)

Dear All, Please ignore my earlier incomplete message with the same title! We are using the ADNI Acc 3D FSPGR for structurals and a 30 directional (5 B0s) dual-spin repeat sequence for DTI (on a 3T GE 750 discovery) which so far rendered really nice results. However, recently I encountered data from several healthy young subjects where the TRACULA fiber tract estimations would suggest severely "crippled" tracts which, however, is not consistent with their FA maps. The crippling is most visible when comparing left vs right cingulate gyri. In some cases either the left or right side is almost completely gone. Has anyone else experienced similar issues and found a remedy? Thanks a lot, Ansgar