cgroups v2: cgexec causes "cgroup change of group failed"

Question

When I try to use cgexec, I get the error message "cgroup change of group failed".

This is how I'm setting up:

CGROUPS_DIR='/sys/fs/cgroup'
createdGroup_dir="$CGROUPS_DIR/createdGroup"

if ! [ -d "$createdGroup_dir" ]; then

    mkdir -p "$createdGroup_dir"/leaf

    echo +cpu +cpuset +io +memory +pids > "$createdGroup_dir"/cgroup.subtree_control

    echo 3G > "$createdGroup_dir"/memory.high
    echo 18G > "$createdGroup_dir"/memory.max

    chown -R user:user "$createdGroup_dir"/leaf
fi

This is how I'm trying to execute (as user):

cgexec -g memory:createdGroup /absolute/path/to/executable

This is what is output:

cgroup change of group failed

I'm using ubuntu 22.04c (c means with 6.1.0-1009-oem kernel. I tried the other options but the result is the same)

I'm using cgroup-tools/jammy,now 2.0-2 which is supposed to support cgroupsv2.

What am I missing?

Thanks in advance for your help!