OData ServiceRequestServiceReferenceObjectCollection filter by InstallationPointID doesn't work

[DisplayName2]

This oData query to ServiceRequestServiceReferenceObjectCollection:

https://my.crm.ondemand.com/sap/c4c/odata/v1/c4codataapi/ServiceRequestServiceReferenceObjectCollect... eq 'SERIALID'&$select=ObjectID,InstallationPointID&$format=json

gives me two entities:

{
    "d": {
        "results": [
            {
                "ObjectID": "025B31541C561EDD8AA312A531497E8C",
                "InstallationPointID": "4047"
            },
            {
                "ObjectID": "06A84A6744FC1EDD8BEB170B54B85066",
                "InstallationPointID": "4047"
            }
        ]
    }
}

So, this query should work: (filter by InstallationPointID eq '4047')

https://my.crm.ondemand.com/sap/c4c/odata/v1/c4codataapi/ServiceRequestServiceReferenceObjectCollect... eq '4047'&$select=ObjectID,Inst
allationPointID&$format=json

but it doesn't, I get response with code 200 and empty results:

{
    "d": {
        "results": []
    }
}

This entity field is marked as filterable in $metadata:

<EntityType Name="ServiceRequestServiceReferenceObject" c4c:parent-entity-type="ServiceRequest">
	<Key>
		<PropertyRef Name="ObjectID"/>
	</Key>
	<Property Name="ObjectID" Type="Edm.String" Nullable="false" MaxLength="70" FixedLength="true" sap:creatable="false" sap:updatable="false" sap:filterable="true"/>
	<Property Name="InstallationPointID" Type="Edm.String" Nullable="true" MaxLength="40" FixedLength="true" sap:creatable="true" sap:updatable="true" sap:filterable="true"/>
	<NavigationProperty Name="ServiceRequest" Relationship="c4codata.ServiceRequest_ServiceRequestServiceReferenceObject" FromRole="ServiceRequestServiceReferenceObject" ToRole="ServiceRequest"/>
</EntityType>