Hi, when booting into a busybox and then use the command 'blkid' to find the UUID for a given device btrfs devices are not shown there. I've tested this with my root device (a SSD) and with a pendrive. Therefore 'findfs' can't find the device for a given UUID/LABEL. Thats bad if you want to mount your root device with via a UUID/LABEL.
Ok, my fault. The "bug" isn't in 1.17.1, just tried that version and it works. Sorry!