The in-lines of the navigation property at second level is coming as initial after XML transformation in backend system ?

We are trying to create an entity with associations as below:

1. Open Order KPI (Key: KPI ID, Navigation Property: NavToDate)
   • Orders aggregated by Date (Key: KPI ID and Date, Navigation Property: NavToOrders)
     • Orders for the Given Date (Key: KPI ID, Date and Order No.)

We have implemented the get deep entity method in the extension for data provider class of the entity to return data for both navigation properties.

URL: /sap/opu/odata/sap/Z_3M_UX_OTC_SRV/OrderSet?$format=json&$expand=NavToDate/NavToOrders

The get deep entity set method is working fine and it is fetching and populating both navigation properties, but in the XML transformation method the in-lines of NavToOrders association are getting refreshed and changed to initial values.

All related SAP notes for this issue are implemented in the back end system. Still we are facing the issue of in-lines being initial, please advice on how to correct the same.