C# EWS项在执行代码时丢失loaded属性

我正在尝试加载和使用EWS项目的属性。在我的代码执行过程中，对象失去了它的值。 Im正在加载消息ID、附件和主题

            FindItemsResults<Item> items = EwsHelper.GetMails(credentials);  //Gets the items from the exchange service object. This method populate FindItemResults. It works.

            //Find correct EmailMessage with messageId (mailInput.MessageId is a param to my code to verify that I found the correct mail.
            string messageId = mailInput.MessageId;                             
            //The Id.UniqueId can be found. The property is loaded inside of the "EwsHelper.GetMails".
            foreach (Item item in items.Where(i => i.Id.UniqueId == messageId))
            {
                //Here im loading all the properties I need once again. I can verify that the object does have loaded property through the debugger. Everything is fine!
                item.Load(new PropertySet(ItemSchema.Subject,
                    ItemSchema.Id, ItemSchema.Attachments));
                if (item == null || !(item is EmailMessage))
                    throw new Exception();

                dynamic fileObj = new ExpandoObject();                  
                //Here the item.Subject (which recently was loaded) is null... Cant figure out why?!
                fileObj.Filename = $"{item.Subject.RemoveInvalidFileNameChar()}.msg";
            }

这是我的密码：

            FindItemsResults<Item> items = EwsHelper.GetMails(credentials);  //Gets the items from the exchange service object. This method populate FindItemResults. It works.

            //Find correct EmailMessage with messageId (mailInput.MessageId is a param to my code to verify that I found the correct mail.
            string messageId = mailInput.MessageId;                             
            //The Id.UniqueId can be found. The property is loaded inside of the "EwsHelper.GetMails".
            foreach (Item item in items.Where(i => i.Id.UniqueId == messageId))
            {
                //Here im loading all the properties I need once again. I can verify that the object does have loaded property through the debugger. Everything is fine!
                item.Load(new PropertySet(ItemSchema.Subject,
                    ItemSchema.Id, ItemSchema.Attachments));
                if (item == null || !(item is EmailMessage))
                    throw new Exception();

                dynamic fileObj = new ExpandoObject();                  
                //Here the item.Subject (which recently was loaded) is null... Cant figure out why?!
                fileObj.Filename = $"{item.Subject.RemoveInvalidFileNameChar()}.msg";
            }

'''

            FindItemsResults<Item> items = EwsHelper.GetMails(credentials);  //Gets the items from the exchange service object. This method populate FindItemResults. It works.

            //Find correct EmailMessage with messageId (mailInput.MessageId is a param to my code to verify that I found the correct mail.
            string messageId = mailInput.MessageId;                             
            //The Id.UniqueId can be found. The property is loaded inside of the "EwsHelper.GetMails".
            foreach (Item item in items.Where(i => i.Id.UniqueId == messageId))
            {
                //Here im loading all the properties I need once again. I can verify that the object does have loaded property through the debugger. Everything is fine!
                item.Load(new PropertySet(ItemSchema.Subject,
                    ItemSchema.Id, ItemSchema.Attachments));
                if (item == null || !(item is EmailMessage))
                    throw new Exception();

                dynamic fileObj = new ExpandoObject();                  
                //Here the item.Subject (which recently was loaded) is null... Cant figure out why?!
                fileObj.Filename = $"{item.Subject.RemoveInvalidFileNameChar()}.msg";
            }

FindItemsResults items=EwsHelper.getMail（凭证）//从exchange服务对象获取项。此方法填充FindItemResults。它起作用了。
//使用messageId查找正确的EmailMessage（mailInput.messageId是我的代码的参数，用于验证我是否找到了正确的邮件。
字符串messageId=mailInput.messageId；
//可以找到Id.UniqueId。该属性加载在“EwsHelper.getMail”中。
foreach（items.Where中的Item（i=>i.Id.UniqueId==messageId））
{
//这里我再次加载我需要的所有属性。我可以通过调试器验证对象是否加载了属性。一切都很好！
item.Load（新属性集）（ItemSchema.Subject，
ItemSchema.Id、ItemSchema.Attachments）；
if（item==null | |！（item为EmailMessage））
抛出新异常（）；
动态fileObj=新的ExpandoObject（）；
//这里的item.Subject（最近加载的）为空…无法理解为什么？！
fileObj.Filename=$“{item.Subject.RemoveInvalidFileNameChar（）}.msg”；
}

---

“”“

错误消息：在读取该属性的值之前，必须加载或分配该属性。如果在使用属性之前重新加载属性，我可以让它工作。但我不想在代码中一直调用EWS。。。

            FindItemsResults<Item> items = EwsHelper.GetMails(credentials);  //Gets the items from the exchange service object. This method populate FindItemResults. It works.

            //Find correct EmailMessage with messageId (mailInput.MessageId is a param to my code to verify that I found the correct mail.
            string messageId = mailInput.MessageId;                             
            //The Id.UniqueId can be found. The property is loaded inside of the "EwsHelper.GetMails".
            foreach (Item item in items.Where(i => i.Id.UniqueId == messageId))
            {
                //Here im loading all the properties I need once again. I can verify that the object does have loaded property through the debugger. Everything is fine!
                item.Load(new PropertySet(ItemSchema.Subject,
                    ItemSchema.Id, ItemSchema.Attachments));
                if (item == null || !(item is EmailMessage))
                    throw new Exception();

                dynamic fileObj = new ExpandoObject();                  
                //Here the item.Subject (which recently was loaded) is null... Cant figure out why?!
                fileObj.Filename = $"{item.Subject.RemoveInvalidFileNameChar()}.msg";
            }