Shared Channels - External User Unable to Consistently View SharePoint Site

[atrain204]

I'm currently testing Shared Channel with an external user account and I'm are having constant issues accessing the SharePoint Team site.

The external account can temporarily access the site for a few moments before the page automatically reloads to the M365 login page.  Then I'm given an error message saying that this user "doesn't exist".

This extends to files on SharePoint too.  The external account can view, create and edit documents but only for a few short moments before they're locked out of the site again. 

Anyone come across this yet?

[#2]

If all the settings required for setting up shared channels are properly configured, this issue should not happen. I recommend you to open a support ticket so the support team can do some troubleshooting and see what might be happening

[#3]

@Juan Carlos González Martín ticket opened and in progress.  Will update this thread if a solution is found, but they found nothing wrong in the initial call.

[#4 · Accepted solution]

Update:  Apparently the external user was NOT added as a guest user in Azure ADD after they were added to my Shared Channel.

The workaround provided by Microsoft support was to have the Global Admin manually invite the user from Azure.  This seems to have addressed the core issue of my external user being disconnected from the SharePoint site.

Of course, this doesn't really explain WHY this happened.  My best guess is that there is a bug in the process to onboard external users to a Shared channel.   However, I couldn't tell you if the core of the issue is really ADD or SharePoint.

So if you come across this issue after adding external users to a Shared Channel, make sure their accounts appear in Azure Active Directory.  It worked for me.