Rock 5B building for NVME

[spriggsy]

I've managed to build AOSP correctly but now having issues on uploading to my device to NVME.

uploading the Radaxa supplied Android nm=vme version works fine
uploading my compiled version states :
<LAYER 2-1> ERROR:RKA_File_Download-->Partition offset is larger than flash size, partition=misc,partition_offset=0x00008000,flash_size=0x00008000

After looking through the logs I've noticed that the Radxa supplied image uploads uboot and then switches the device to loader mode. my images doesn't do this, it tries to upload the image complete. here's the logs for comparison

I think that its trying to upload the complete image to the SPI flash?
how does the uploader know to move to the NVME disk?
I know this can be done as Radxa have managed to do it and have supplied an image proving it.

(success) https://pastebin.com/NnSa0jdv
(failed) https://pastebin.com/Gv6vHrmc

Any help or pointers please

Spriggsy