I have an old and a new app. In both I create appointments in calendars and add extended properties with a custom namespace (Guid) via EWS Managed API. The server is the same.
The old app is running under .NET 4.7.1 and uses Microsoft.Exchange.WebServices (version 1.2), while the new app is running under .NET 6 and uses Microsoft.Exchange.WebServices.NETStandard (version 1.1.3).
I use the below code to add a new property in both apps
var epd = new ExtendedPropertyDefinition(EWS_EXTENDED_PROPERTIES_GUID, "SFRECID", MapiPropertyType.String);
NewEWSAppointment.SetExtendedProperty(epd, Item.GetItemByName(epd.Name).Value);
If I create the appointment in the old app then OutlookSpy (5.0) lists my properties correctly.
If I run the new app then I cannot see them in OutlookSpy,
but I can find the newly created appointment with the same app and the extended properties are returned correctly.
Is there any difference between the full framework implementation of the EWS API and the NetStandard version? How could I change the new app to work the same way as the old? I want OutlookSpy to show them the same way, because there are other apps depending on these properties.
Update: Here is a screenshot of the created appointment in the calendar.
Thanks