Hi @Dahuang. Testing this in VirtualBox and root with btrfs does not work. ext4 and xfs do work.
With btrfs root I get this error,
Failed to unpack image "/run/initramfs/omdv/LiveOS/squashfs.img"
rsync failed with error code 11."/run/initramfs/
I have asked the project leader about this on IRC. You are welcome on IRC if you wish to ask questions or follow the conversation. Patience is required, we are a small all unpaid, part-time, volunteers. Someone will answer in time. People may not be in your time zone, ect.
Post edit: Full Calamares logs of attempt to install using / btrfs partition:
calamares-btrfs-log.txt (45.8 KB)
User note: To get the log of a failed installation you can run Calamares installed from Konsole like this:
$ pkexec calamares -d
and copy and paste all the output to a text file to post that in forum post or bug report. Do not post only the part you think is important, post all the output.