The current version of create-sdcard.sh fails in creating the partition table if a non-english locale is used. The reason is in line 443 and 502:
SIZE=`fdisk -l $DRIVE | grep Disk | awk '{print $5}'`
There the script greps for "Disk", which works only for an english language locale. Here I have a german locale, so this line doesn't deliver the drive size - which consequently broke the following call of sfdisk.
I suggest to change this script so that it changes the locale to C before it does anything else.