Cannot forward a contact group I created to other colleagues anymore?

Hi LL,
Good day! Thank you for reaching out to Microsoft Q&A forum and sharing the detail. 

Based on your information, it's likely something that used to work, forwarding a contact group, suddenly doesn’t behave as expected. 

This issue may occur after updating the group’s email addresses. One possible reason is that the updated contact group may not serialize correctly when forwarded, especially if it includes newly modified or cached entries. Another potential cause is when the contact group includes members from the Global Address List (GAL), and the recipient isn't connected to the same GAL (this can result in the group arriving as a blank attachment). 
 

Please try the following steps to try forwarding your contact group: 

1. Open the contact group in your Contacts. 
2. On the ribbon, select Forward Contact > As an Outlook Contact.

1. Send the message, and the recipient should be able to drag and drop the group into their Contacts folder. 

Note: If the contact group contains members from the Global Address List, please ensure the recipient is also using the same GAL for the group to display correctly. 

If the issue still persists, please feel free to update me. I'll be happy to further investigate and assist you.

Looking forward to your response. 

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