I have been having an issue with the rootfs not being resized on first boot and it causes all the expected problems with no space for the OS to operate.
The UltraZed-EV assigns /dev/mmcblk1 to the SD card. I had to modify the bootargs file to get it to find the rootfs partition during boot.
It seems that the resizefs.sh script is hardwired to resize /dev/mmcblk0. I tried editing the resizefs.sh script in the resizefs package and adding that to my board spec. It seems to work. Does that have any unwanted side effects?