Okay, that confirms my suspicion. However I am not sure what the best solution is. Let me explain:
By default the disk in the m:robe is formatted as a so called 'superfloppy' whereas yours is partitioned like a hard disk. Both are valid approaches and rockbox as such supports both. However we disable the support for partitioned disks in the m:robe port, as it adds up to 28s to the boot time (the detection takes about 14s and happens twice: for the bootloader as well as for rockbox itself). So the options are:
1) re-enable it and suffer through the long boot time
2) have a separate build for you and others with the same issue
3) format your disk as superfloppy
I would like to know how many others have the same issue. If it is just you, I would suggest 3). Are you familiar with task like partitioning and formatting? It is a little bit tricky in Windows, but maybe I can find a tutorial on the web somewhere. Also I am not entirely sure what needs to be done to get the original firmware working again, but you probably have gone through this procedure already, have you? Let me get some opinions from other developers. Maybe they can see a different solution.