i must admit im not sure if i ever tried to format usb under os4, even though as far as i recall the os4 mediatoolbox does allow me to access usbscsi.
maybe rdb is not getting read correctly, wouldnt it be safer to have sfsfilesystem in l: im not sure but i suspect sfs has both 68k and ppc filesystem versions? just checked i even run slightly different version under both system. definitely it has to be some minor issue.