Linq Query that EF doesn't like: DbUnionAllExpression requires arguments with compatible collection ResultTypes. No way to tell it to do the proper projections in memory and just fetch the data! LLBLGen Pro handles it just fine.

LinqQuery.cs

return baseQuery.Select(p__0 => new DTOs.DtoClasses.BoardMemberDTO()
{
	CompanyCar = new DTOs.DtoClasses.BoardMemberDTOTypes.CompanyCarDTO()
	{
		Brand = p__0.CompanyCar.Brand,
		CarId = p__0.CompanyCar.CarId,
	},
	CompanyCarId = p__0.CompanyCar.CarId,
	EmployeeId = p__0.EmployeeId,
	ManagesDepartmentId = p__0.ManagesDepartment.DepartmentId,
	ManagesDepartmentName = p__0.ManagesDepartment.Name,
	Name = p__0.Name,
	StartDate = p__0.StartDate,
	WorksForDepartment = new DTOs.DtoClasses.BoardMemberDTOTypes.WorksForDepartmentDTO()
	{
		Employees = p__0.WorksForDepartment.Employees.OfType<InheritanceOneReverseEngineering.EntityClasses.Employee>()
			.Where(p__1 => !(p__1 is InheritanceOneReverseEngineering.EntityClasses.Manager) &&
							!(p__1 is InheritanceOneReverseEngineering.EntityClasses.Clerk) &&
							!(p__1 is InheritanceOneReverseEngineering.EntityClasses.BoardMember))
			.Select(p__1 => new DTOs.DtoClasses.BoardMemberDTOTypes.WorksForDepartmentDTOTypes.EmployeeDTO()
			{
				Name = p__1.Name,
			})
			.Union(p__0.WorksForDepartment.Employees.OfType<InheritanceOneReverseEngineering.EntityClasses.Manager>()
					.Where(p__1 => !(p__1 is InheritanceOneReverseEngineering.EntityClasses.BoardMember))
					.Select(p__1 => new DTOs.DtoClasses.BoardMemberDTOTypes.WorksForDepartmentDTOTypes.EmployeeManagerDTO()
					{
						ManagesDepartment = new DTOs.DtoClasses.BoardMemberDTOTypes.WorksForDepartmentDTOTypes.EmployeeManagerDTOTypes.ManagesDepartmentDTO()
						{
							DepartmentId = p__1.ManagesDepartment.DepartmentId,
							DepartmentType = p__1.ManagesDepartment.DepartmentType,
							MeetingRoomCode = p__1.ManagesDepartment.MeetingRoomCode,
							Name = p__1.ManagesDepartment.Name,
						},
						ManagesDepartmentId = p__1.ManagesDepartment.DepartmentId,
					}))
			.Union(p__0.WorksForDepartment.Employees.OfType<InheritanceOneReverseEngineering.EntityClasses.Clerk>()
					.Select(p__1 => new DTOs.DtoClasses.BoardMemberDTOTypes.WorksForDepartmentDTOTypes.EmployeeClerkDTO()
					{
						JobDescription = p__1.JobDescription,
					}))
			.Union(p__0.WorksForDepartment.Employees.OfType<InheritanceOneReverseEngineering.EntityClasses.BoardMember>()
					.Select(p__1 => new DTOs.DtoClasses.BoardMemberDTOTypes.WorksForDepartmentDTOTypes.EmployeeBoardMemberDTO()
					{
						CompanyCarId = p__1.CompanyCar.CarId,
					}))
			.ToList(),
		Name = p__0.WorksForDepartment.Name,
	},
	WorksForDepartmentId = p__0.WorksForDepartment.DepartmentId,
});