How to perform map, when mapping relies on previous map config? - automapper

Question

The below mapping between Volunteer & IVolunteerViewDTO works perfectly fine. I can call a REST api and receive a list of IVolunteerViewDTO mapped using AutoMapper. However, I can't figure out how to get Registration working with IRegistrationDTO. AutoMapper throws an exception and says: InvalidCastException: Unable to cast object of type 'Proxy<RSMuseum.Services.DTOs.IVolunteerViewDTO_RSMuseum.Services_Version=1.0.0.0_Culture=neutral_PublicKeyToken=null>' to type 'RSMuseum.Services.DTOs.VolunteerViewDTO'.
public IMapper GetMapper()
{
var mc = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Volunteer, IVolunteerViewDTO>()
.ForMember(dest => dest.GuildName,
opts => opts.MapFrom(src => src.Guilds.Select(x => x.GuildName)))
.ForMember(dest => dest.FirstName,
opts => opts.MapFrom(src => src.Person.FirstName))
.ForMember(dest => dest.LastName,
opts => opts.MapFrom(src => src.Person.LastName));
cfg.CreateMap<Guild, IGuildDTO>();
cfg.CreateMap<Repository.Entities.Registration, IRegistrationDTO>()
.ForMember(dest => dest.Guild,
opts => opts.MapFrom(src => src.Guild))
.ForMember(dest => dest.Volunteer,
opts => opts.MapFrom(src => src.Volunteer));
});
mc.AssertConfigurationIsValid();
IMapper m = new Mapper(mc, t => _container.GetInstance(t));
return m;
}
The dest.Volunteer is the DTO and the src.Volunteer is the entity itself. When I comment out the need for the VolunteerDTO on my RegistrationDTO, everything is perfectly fine and no exceptions at all. Question is how to fix.