I’ve also had issues with the firmware thinking boot/ is empty. It’s more superstition than science, but following the procedure below fixes it for me when that happens.
sudo mkfs.ext4 -O ^metadata_csum,^64bit /dev/[sd_card_device_partition]
...[extract files to sd card]...
sudo mkdir /path/to/sd_card/boot
sudo cp Image armada-3720-community.dtb /path/to/sd_card/boot
sync
