$notDeletedPK - ID's of models came null

[I-NOZex]

yii2-relation-trait/RelationTrait.php

Line 230 in 8149499

$relModel->deleteAll($query);

In line 190...199, when getting the primaryKey, it cames null, i could not figure why, it seems that after the save, the related model loses the primarykey/id
Could you investigate?
Thank you