Property change on object chnage not triggering?

[taxinvoice]

MY CODE
[ObservableProperty]
public CustomerDto selectedCustomer = new CustomerDto();

    ....
   CustomerDto customerNow = _mapper.Map<CustomerDto>(custNow); 
    SelectedCustomer = customerNow; 
    **//assigning to the property.   BUT   partial void OnSelectedCustomerChanged(CustomerDto value) never triggering**

GENERATED CODE
public global::Xrm.Models.CustomerDto SelectedCustomer
{
get => selectedCustomer;
set
{
if (!global::System.Collections.Generic.EqualityComparerglobal::Xrm.Models.CustomerDto.Default.Equals(selectedCustomer, value))
{
OnSelectedCustomerChanging(value);
OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.SelectedCustomer);
selectedCustomer = value;
OnSelectedCustomerChanged(value);
OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.SelectedCustomer);
}
}
}

    How does EqualityComparer compare the object and how do trigger the property change event?  Spent 2 days on thisd already, must eb an easy answer i would hope :