EFCore override SaveChangesAsync does not save entity

public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default){    foreach(var entry in base.ChangeTracker.Entries<BaseDateEntity>()        .Where(q => q.State == EntityState.Added || q.State == EntityState.Modified))    {        var dateTime = DateTime.Now;        var persianCalendar = new PersianCalendar();        var year = persianCalendar.GetYear(dateTime);        var month = persianCalendar.GetMonth(dateTime).ToString("D2"); ;        var day = persianCalendar.GetDayOfMonth(dateTime).ToString("D2");        var hour = persianCalendar.GetHour(dateTime).ToString("D2"); ;        var minute = persianCalendar.GetMinute(dateTime).ToString("D2");        if (entry.State == EntityState.Added)        {            entry.Entity.CreatedDateTime = dateTime;            entry.Entity.CreatedTime = $"{hour}:{minute}";            entry.Entity.CreatedDate = int.Parse($"{year}{month}{day}");        }        if (entry.State == EntityState.Modified)        {            entry.Entity.LastModifiedDate = int.Parse($"{year}{month}{day}");            entry.Entity.LastModifiedTime = $"{hour}:{minute}";        }    }    return base.SaveChangesAsync(cancellationToken);}

I have overrided the Savechanges method of EFCore.It does not add the entity to the database.When I change the last line to

var res =  base.SaveChangesAsync(cancellationToken).Result;return Task.FromResult(res);

It worksWhat is the reason ?