Guest user can't add a comment to Planner task

[ALR12285]

Hello everyone,

as soon as a guest user wants to send a comment in a Teams Planner task, they get the error message "Your session has expired. Can you please log in again?...".

The general access to Teams Planner for guest users work (i.e. they can create and edit tasks etc.), only sending comments does not work.

We have already checked the solution in the following link and deleted the "MailContact" entry for the user. But it still does not work.
https://learn.microsoft.com/en-us/office/troubleshoot/planner/guests-cannot-comment-assigned-tasks

Is there a suggested solution for this?

Many thanks in advance!

[#2]

@ALR12285 I'm not sure if we have a related problem, but our Guest users can see the Teams Planner tasks but are unable to change anything: no Notes, no Remakrs, unable to assign a task to a user etc.

They get a message saying they ar not authorized to view mebers of the Microsoft 365 group.

Strangely enough, if a guest goes to de Planner hub everything works fine.

Possibly a recent bug in the Teams Planner?

[#3]

@Kees_van_Elk Thanks for your comment! Unfortunately on Planner Hub is no comment function. Everything else works.