Hi @DucourtyEtan ,It seems to me that you can have some issue with filtering or paging.I will share with you a simplified example of two custom entities with a parent-child relationship. There you also find the example of code that handles filtering,...

Hi @jdpaul_jabez ,Assign the business catalog SAP_CORE_BC_EXT_TST to your user, it should solve the issue.Also you can check following links:SAP Note - https://userapps.support.sap.com/sap/support/knowledge/en/3399748 Documentation - https://help.sap...