Hello JONATHAN RUDMAN,
Welcome to Microsoft Q&A Forum.
From your description, I understand that you are experiencing the "Congratulations" message appears during the invitation process, but the share fails to activate if the recipient hasn't fully joined your Microsoft family group or if there's a backend delay.
Microsoft 365 Family subscription allow sharing up to 5 others, but the process requires the invitee to select "Join now" from their email and complete family group.
Here are some steps that you can kindly follow to help resolve this:
- Verify your subscription type that shows "Share subscription"
- Have the invitee check junk mail, accept via the link, and ensure they are not in another family group or have their own M365 subscription.
- You can kindly follow the instructions from this article: Share your Microsoft 365 Family or Premium subscription.
If none of the steps below work, you can kindly contact Microsoft Support again or consider purchasing a separate Family plan as a workaround.
Please note: As forum moderators, we do not have the authority to gain access to your account/device or internal resources to personally fix the issue. Thank you for your understanding
Thank you for your time and patience, I hope you have a great day.
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