I typically used the following in a terminal window on Ubuntu to burn the rasbian image to a SD card:
sudo dd bs=4M if=2018-06-27-raspbian-stretch.img of=/dev/sdb
then a sync command.
Most of the time, it results in a corrupt SD card that won't boot.
But, if I run the exact commands again on the card, it results in a bootable SD.
The other day I used etcher and had the same experience.
Any idea why this would be?