Saving multiple objects with same object property EF core

I have this situation: I have a MasterPlanComponent object that holds multiple objectives. These objectives hold multiple targets.

Upon creating a masterPlanComponent (with 2 objectives) we create 4 targets for both of those objectives.

This is what that's supposed to look like:

• 1 component > 2 objectives > 8 targets (4 for one, 4 for the other, targets are blank and just need to be created in the database)

The problem with the below code is that only one set of 4 targets are created, and only for the second objective.

public async Task<MasterPlanComponent> CreateMasterPlanComponent(int masterPlanId, CreateMasterPlanComponentCommand command) 
{

    var masterPlan  = await _context.MasterPlans
        .Include(mp => mp.Components)
        .Include(mp => mp.Objectives)
        .SingleOrDefaultAsync(m => m.MasterPlanId == masterPlanId);

        var targets = new  List<ObjectiveNetTarget>();
    //creating new targets and setting two of their fields
    for (int i = 0 ; i < 4 ;  i++)
    {
        targets.Add(new ObjectiveNetTarget
        {
            CustomerMarketSegment = command.Scope.CustomerMarketSegment,
            OrganizationUnit = new OrganizationUnitRef
            {
                Name = "Sales",
                Code = "1251"

            }
        });

    }
    var masterPlanComponent = Mapper.Map<CreateMasterPlanComponentCommand, MasterPlanComponent>(command);
    foreach (var objective in masterPlanComponent.Objectives)
    {
        objective.TargetValues = new List<ObjectiveNetTarget>(targets);
    }

    masterPlanComponent.Status = MasterPlanComponentStatuses.New;
    masterPlan.Components.Add(masterPlanComponent);
    masterPlan.Objectives = masterPlan.Objectives.Concat(masterPlanComponent.Objectives).ToList();
    //masterPlanComponent.Objectives targets, I can see that both of them have 4 net targets as it should be
    await _context.SaveChangesAsync();

    _logger.LogInformation("New master plan component created.");
    _logger.LogInformation("Master plan component id: " + masterPlanComponent.ComponentId.ToString());
    //after I try to save the context however, only one of them has it. 
    return masterPlanComponent;
}

this code results in only 4 targets being written in the database each of them pointing to only one (the last one) of the objectives