3388096 - Customized itemtype items got deleted when unlinking from Parent Product

Found one of customized item named "customertype" got auto removed after it unlinked with OOTB data type Product: 

<relation code="Product2Allergen" autocreate="true" generate="true" localized="false">
    <sourceElement qualifier="product" type="Product" cardinality="many" metatype="Customertype">
        <modifiers read="true" write="true" search="true" optional="true" removable="false" initial="false" unique="false" private="false" partof="false"/>
        <deployment table="prd2allergenrelation" typecode="30014"/>
    </sourceElement>
    <targetElement qualifier="customertype" type="Customertype" cardinality="many" metatype="Product">
        <modifiers read="true" write="true" search="true" optional="true" removable="false" initial="false" unique="false" private="false" partof="true"/>
    </targetElement>
</relation>

SAP Commerce Cloud

unexpected deleted. , KBA , CEC-SCC-PLA-PL , Platform , Problem