By the way, the same error occurs with gsettings:
$ gsettings get org.compiz.core:/org/compiz/profiles/unity/plugins/core/ hsize
1
$ gsettings set org.compiz.core:/org/compiz/profiles/unity/plugins/core/ hsize 3
$ gsettings get org.compiz.core:/org/compiz/profiles/unity/plugins/core/ hsize
1
$
By the way, the same error occurs with gsettings: core:/org/ compiz/ profiles/ unity/plugins/ core/ hsize core:/org/ compiz/ profiles/ unity/plugins/ core/ hsize 3 core:/org/ compiz/ profiles/ unity/plugins/ core/ hsize
$ gsettings get org.compiz.
1
$ gsettings set org.compiz.
$ gsettings get org.compiz.
1
$