Shared channel not adding external users (One way issue)

[jwardhana]

Hello everyone,

Hope someone can provide insight to this, i've been trying to find solution for the past few days to no avail.

Background:

• Create shared channel between 2 organizations (My organization and the opposite organization)
• Both organizations  have set up all B2B Direct connect inbound/outbound settings in cross-tenant access settings (Azure AD)
• Both organizations have ensured teams settings and shared channels are enabled. (Teams admin control centre)
• My organization is able to add the opposite organization into the teams channel as guest (in standard channel)

Issue:

• The opposite organization is able to add me into their shared channel without any issue.
• When i try to add the member of the opposite organization, the following message popped up

Solutions attempted:

• Adding the member from the Microsoft Teams admin control centre.
• Checked and confirmed that settings under admin.microsoft.com > settings > org settings > services | Microsoft Teams & Microsoft 365 Groups are identical for both organizations.
• Deleted the guest user and re-created again in admin.microsoft.com > users > Guest users > add new guest users via invitation (AzureAD) which led to the above screen cap scenario 
• B2B collaboration and B2B direct connect in azure AD cross-tenant access settings all set up properly and identical for both organizations

References:

• https://learn.microsoft.com/en-US/microsoft-365/solutions/collaborate-teams-direct-connect?WT.mc_id=...
• https://learn.microsoft.com/en-us/MicrosoftTeams/shared-channels#shared-channel-limits
• https://learn.microsoft.com/en-us/microsoftteams/shared-channels-errors
• https://learn.microsoft.com/en-us/microsoftteams/teams-policies
• https://learn.microsoft.com/en-us/azure/active-directory/external-identities/cross-tenant-access-set...

[#2]

A shared channel is using B2B Direct connect and not B2B, meaning you can't add a guest user to a shared channel. They have to be invited from the shared channel using their email address. If you can't send the invite you have some org. setting preventing that. Hopefully you can use the guidance here https://learn.microsoft.com/en-us/microsoftteams/shared-channels-errors

[#3]

Hi Christian,
I have outlined all that in my message.
1. Both organizations have already set up the B2B Direct connect properly and still not able to invite the user. The closest i can get is to re-invite the user as guest, in which they appear on the name list when i type in their name in shared channel, but i got stuck at the part shown in my screen capture above.
2. I have gone through all the guidance available (as indicated in the reference) to no avail.

[#4]

Sorry, cannot recreate your experience when setting up B2B direct connect between two test tenants. Even though I have blocked external access (federation) I can still invite Direct connect users from that org. in the shared channel with only the [External] suffix. Could possibly be a delay involved, but have no idea how long you've waited. Perhaps better off creating an official support ticket with Microsoft so they can look into it.

[#5]

I am experiencing the exact same issue and error message right now :

On tenant A, I can add users from tenant B to a test shared channel I created, but on tenant B, I can't add users from tenant A...

Have you been able to solve this since the last answers you got?

[#6]

I have exact SAME issue... is there any fix for this ?! One change we did however is move our CA Policies to Authentication Strength if it's relevant....

[#7]

I just started having this exact same issue 2 weeks ago. Nothing changed in our environment. We have been using shared channels for almost a year and then all of a sudden one day they stopped working in one direction only. Super frustrating for our users. I have an open support ticket but none of their suggestions are working. I even tried submitting a service alert at it was rejected as a non service related problem. I'm really disappointed that others haven't had a resolution since last year after reading this post.