Upgrading Phalcon 2 to 3 - difference in model relations

Hello everyone,, we're updating a large application from Phalcon 2 to 3. We've found that model relations behave differently. I can't find anything in the changelog and was hoping someone could help explain.

It seems that in Phalcon 2, relations are refreshed on each access. In Phalcon 3 the related object is stored and not refreshed. Is this correct?

Here is an example of sorts with a unit test, I can post more code if helpful:

// say we have a robot with 2 parts
$this->assertEquals(2, count($robot->Parts));

// add a new part without referencing the relation
$part = new Part();
$part->name = 'Arm';
$part->robotId = $robot->Id;
$part->save();

// the robot now has 3 parts
$this->assertEquals(3, count($robot->Parts));

In Phalcon 2 this works - $robot->Parts is correctly updated when I check the 2nd time. In Phalcon 3 the behaviour is different. The first access to robot->Parts caches the object and it is n longer refreshed.

I can't find this in the documentation on upgrading. Thanks!