The error message you are encountering is indicating that the properties you are trying to use as single-valued navigation properties are not declared in the OData model.
In OData, only declared navigation properties and declared named streams can be represented as properties without values. To resolve this issue, you need to declare these properties in the OData model.
You can find more information on how to declare navigation properties in OData in the following link: https://docs.oasis-open.org/odata/odata/v4.0/errata03/os/complete/part3-csdl/odata-v4.0-errata03-os-part3-csdl-complete.html#_Toc453752347
Please let us know if you have any further questions or concerns.