[VSTO/Outlook] ContextMenuContactCardRecipient callbacks not always called

Question

Hi,

I am struggling with an issue using idMso ContextMenuContactCardRecipient menus in my Outlook VSTO add-in.

On a random basis, my custom menu entries become inactive and empty (no label, no action). The contextual menu only displays the "placeholders" of my menu entries. When this happens, the callbacks I defined in the XML file are not called at all (getVisible, getLabel,...).

It seems to be linked with Outlook context switch: the menu can work or stop working after switching from an explorer window to a contact inspector window for example. When broken, opening a contact inspector, switching from mail explorer view to calendar view for example may repair it.

You can see in the attachments how is displayed the menu when the issue happens, and when is does not happen:

I easily reproduced the exact same issue with a 3rd party add-in sample provided by the AddInExpress team (found here: https://www.add-in-express.com/creating-addins-blog/2015/04/15/creating-office-context-menu-addin/). It brings one ContextMenuContactCardRecipient menu entry.

And found this forum post explaining the same problem (with unfortunately no solution): https://social.msdn.microsoft.com/Forums/vstudio/en-US/1000c714-0562-47af-a77d-244b51d410ab/outlook-contextmenucontactcardrecipient-customizations-seem-to-be-unreliable?forum=vsto

My add-in uses other idMso for other extensions (ribbons, other contextual menus) and the idMso ContextMenuContactCardRecipient is the only one showing this issue.

I currently use:
Outlook for Office 365 MSO (16.0.12527.20170) 32bits
VSTO 10.0.60828
Visual Studio Professional 2019 version 16.10.3
Windows 10 Professional 19041.1348

Thanks in advance for your help / support !

Fabrice.