store sync fails

[jesa]

Hi all!
I've found a strange issue, what am I missing here?
I have a form with button that saves changes to record
If I use this

updateHandler: function () {
    var record = this.getRecord();
    var values = this.getValues();
    record.set(values);    //store configured to autosync
    this.destroy();
}

my updating fails, see attached file for stacktrace

1.jpg

If I use

updateHandler: function () {
    var record = this.getRecord();
    var values = this.getValues();
    record.set(values);
    record.save(); //store autosync is off, proxy declared specially for current model
    this.destroy();
}

everything is OK

What I need to change in store/model to fix this? Thanks

ExtJs 6.2.0

[jesa]

I've found the solution: fields for Model were defined in Model's constructor(), when moved them to static config - all became good)