loadOptions always returns No sub-options

[ecuci]

My normalizer looks like this:
normalizer(node) { return { id: node.id, label: node.name, children: node.child?.data, }; }

and I use both LOAD_CHILDREN_OPTIONS and ASYNC_SEARCH

when I set at case of LOAD_CHILDREN_OPTIONS
this:
parentNode.child = { data: children };
or that:
parentNode.child.data = children;

and then
callback();

normalizer does not work and it says No sub-options all the time.