Incorrect ID being set after ActiveRecord save - php

Question

So I'm encountering a weird bug that is happening, but only some of the time. I can't seem to nail down anything that's causing it to happen. Basically, I have a ActiveRecord which corresponds with a table in my DB. I assign values to a object and call save().
Lets say I have the following code:
$student = new Student();
$student->name = "Gregg";
$student->surname = "Smith";
$student->gender = "Male";
$student->save();
Then my Student active record model I have the following:
public function afterSave()
{
$this->assignStudent($this->id);
}
$this->id IS not the correct ID after saving. I can see the ID in the log being 1416253 while the ID in the DB for that record is 670336. How can something like this happen?
UPDATE
I've done some more investigation and it seems that $this->id is assigned by assigning the last insert id back after doing the insert. Except that it is not returning the ID for the save() insert, but for a insert that was done previously (The insert in question was into the log table). This means that the insert into the student table is, according to the system, not happening correctly (even though it is, because I can see the record in the DB).

Answer 1

I am not sure how a wrong id can appear. Does the wrong id match another record of the table?
Have you tried something like this to be sure to be up to date ?
public function afterSave()
{
$this->refresh();
$this->assignStudent($this->id);
}
Also, the documentation states "When overriding this method, make sure you call the parent implementation so that the event is triggered" (documentation afterSave). So I think the correct way of writing all this may be:
public function afterSave($insert, $changedAttributes)
{
parent::afterSave($insert, $changedAttributes);
$this->refresh();
$this->assignStudent($this->id);
}