Image generation script creates 1K image file

I am using this derivative of Robert’s eMMC → img file script

https://elinux.org/BeagleBone_Black_Extracting_eMMC_contents

and it runs instantly and creates a 1K image file. I suspect something has changed since that Wiki entry was created.

I have tested this on both Element 14 and Beagleboard versions of BBB.

Here is my uEnv.txt file:

bootpart=0:1 bootdir= fdtaddr=0x81FF0000 optargs=quiet capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN uenvcmd=load mmc 0 ${loadaddr} uImage;run loadfdt;setenv bootargs console=${console} ${optargs};bootm ${loadaddr} - ${fdtaddr}

and I have

am335x-boneblack.dtb

in root and /dtbs

Thanks!