clRFU 10.64 not working

I’ve been trying to use clRFU.exe command line application to enable a binary to be uploaded to my targets. I’m using the command line version thus

clRFU project.bin -s 3:115200 -cl .\coldload.bin -pb .\pilot.bin -usb+ -v

I’ve obviously copied the files from DCRabbit_10.64\Bios into the standalone directory and as long as the c:\DCRabbit_10.64\Bios directory is also present it all works fine. If I rename or remove the Bios directory or indeed the whole c:\DCRabbit_10.64 tree as would be the case for remote users upgrading the firmware I get the error

Sending Coldloader
Error: Could not open cold loader file.

However if I copy over and use the clRFU.exe from version DC10.60 it all works fine standalone. I can only assume that the -cl and -pb command line parameters aren’t working for DC10.64. The same applies to clRFU.exe from DC10.62.

Has anyone else had this issue at all and is there a fix other than using the older loader? I need to issue an update package for product in the field.