Ok, so this seems like bug in ke-recv.

Please attach syslog, maybe there will be something interesting.

How ke-recv should use mount dest:
* first FAT32 partition on SD card is mounted to /media/mmc1
* if there is no FAT32 partition, first partition (any FS) is mounted to /media/mmc1
* all other partitions are mounted to /media/mmc1p<number> where number is partition number
* max partitions on mmc devices (both eMMC and SD cards) are limited to 8 by kernel