Strange behaviour of the method 'save' within the helper

[vmusulainen]

I have faced with strange behaviour of 'save' method.
I have a class Unit that is extended on server side

Unit.extend({
    meteorMethods: {
        insert() {
            this.name = 'insert name';
            const id = this.save();
            const parentUnit = Unit.findOne({_id: this.parentUnitId});
            console.log('parentUnit', parentUnit);
            parentUnit.changeName();
        },
    },
    methods: {
        changeName(){
            console.log('change name is called');
            this.name = 'changed name';
            console.log(this);
            this.save()
        }
    }
});

When I call method 'insert' from client side like this:

const unit = new Unit({
                name: 'New Unit Name',
                parentUnitId: this.selectedUnitHolder.get()._id,
            });

unit.callMethod('insert');

I get properly stored new unit in db, but parent unit is not updated although console output from changeName method look as

Class {
	_isNew: false,
	_id: 'jiM8ZXBuayz6H4Za5',
	name: 'changed name',
	parentUnitId: undefined}

The field 'name' of parent unit has non-changed value in db.

But! the saving in method work as expected if I call it for the original object like this

Unit.extend({
   meteorMethods: {
       insert() {
           this.name = 'insert name';
           const id = this.save();
           //const parentUnit = Unit.findOne({_id: this.parentUnitId});
           //console.log('parentUnit', parentUnit);
           this.changeName();
       },
   },
   methods: {
       changeName(){
           console.log('change name is called');
           this.name = 'changed name';
           console.log(this);
           this.save()
       }
   }
});