In case anyone else encountered this problem. You have to edit your function and check the "has return value" box. Then your return will work. After this you have to use "Call Function" again and now you have a new field for saving results.
@allister Hi, this is bug, it happens only if update column of int type. It was fixed, new version will be available in Thursday(8 November), if it is urgent for you, I can make a separate build.