DISM /apply-ffu fails with exit code 21 / 443 when applying image from USB

Question

When are using DISM to apply a ffu image to a device when updating the OS Image of the device. We are facing issues that we cannot explain.

The sequence that takes place is:

1. Insert USB disk with ffu file to apply to device
2. Boot the device into WinPE RAM using bcdedit
3. After WinPE is loaded execute this command in startup script:
   DISM /apply-ffu /ImageFile:[The image] /ApplyDrive:[The physical disk of the device]
4. After approx. 80% the DISM command fails with either error code 21, or 443
5. Running the command again will always work successfully

We have tried different USB disks but the same result.

The log file displays some errors but its difficult to figure out the root cause.

DISM.log