Can't boot Silverblue installed on BTRFS subvolume

The subvolume with mount point ‘/’ was created in BTRFS volume at install time with it’s Advanced Manual Partitioner.

Installation went without errors, but can’t boot it with:

ostree-prepare-root: Couldn't find specified OSTree root 'sysroot//ostree/boot.0/fedora/\<hash>/0' : No such file or directory

Any workaround possible? I need definitely use BTRFS subvolume.
Thanks for any help.

Here is the problem described: