Json custom de-serializer not called when receiving data using FromQuery (query param)

Hey.
i am using the latest asp.net core RC2 in a web api project.
i have a type with costume serializer and de-serialize. when i return the type as the body of request the serializer is called and the expected string is sent back to the client.
how ever, when the client sends the same formatted string as query param (http://localhost:5000/api/?data=3f95e49e-a2f0-4a7d-9bb8-ad2c13e23260) the custom de-serializer is not called and the returned type is empty.

in other scenarios the custom de-serializer works great.

is it a bug?

Thanks Yosi