New Setting in Teams App Setup Policy
Office 365 Notification MC202761 (January 31) and its follow-up MC202765 (to apologize that Microsoft started to deploy the update before announcing it) inform tenants that Teams App Setup policies include a new setting to control if users can customize the set of apps in the left navigation rail in the desktop and browser clients or the bottom of the screen for mobile clients. The setting is turned on by default and all tenants should be able to change the Allow user pinning setting in Teams App Setup policies (Figure 1) by the end of February 2020.

Apart from the Teams Admin Center, you can also update App Setup policies using PowerShell. For instance, here’s how to scan for all policies in the tenant that currently allow user app pinning to update the setting to Off.
# Get all Teams App Setup policies, find those that allow app pinning # and update them to disable app pinning Get-CsTeamsAppSetupPolicy |?{$_.AllowUserPinning -eq $True} | Set-CsTeamsAppSetupPolicy -AllowUserPinning $False
It can take a couple of hours before a change in an App Setup policy is respected by clients. App pinning is only supported for tenant users. Guest users are restricted to a default set of apps (Activity, Teams, Chat, and Files).
Pinning and Unpinning Apps
When the app setup policy assigned to their account allows app pinning, users can pin an app by selecting it from the Apps menu (sometimes displayed as [...]) and then choosing Pin from the right-click menu (Figure 2). When an app is pinned, Teams displays the app icon in the left-hand navigation rail. In Figure 2, Planner is an example of a pinned app.

When the App Setup policy assigned to their account blocks app pinning, the user doesn't see the pin option (Figure 3).

If the Teams App Setup policy assigned to an account is updated to block user app pinning, Teams removes any apps pinned to the left-hand navigation bar. If the policy is then updated to allow user app pinning, users mist re-pin their pinned apps.
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We have “Allow user pinning” turned on in our Global policy but yet our users get “Your admin has updated your settings. Some of your pinned apps may have moved” when trying to pin apps. Anyone else have this problem?
We have noticed that when a user pins apps to their Teams Client, when signing out & back in, the pinned Apps are not remembered – is that expected behaviour?
Nope. The client should remember.
Hmm ok – might need to give MS a call then.
Also noticed that i cant pin planner anymore…
Mind you, User-Voice & 365Roadmap still saying working on it & rolling out, so will wait and see..
We are experiencing this same behavior. Under Setup Policy, the Global (org-wide default) policy allows user pinning. We continually have users pin Planner and OneNote to the left hand side, but then they get the admin message as mentioned above and the apps disappear from the left hand side bar.
I’ve seen some other reports of this kind of thing. Please file a support ticket with Microsoft. The more reports come in, the quicker this will get fixed.
We’ve also experiencing the same faulty behaviour. (NL-Enschede). Any luck with some progress ?… or maybe somebody has a some link to an statement of Microsoft self about this issue ?
The official documentation is at https://docs.microsoft.com/en-us/microsoftteams/teams-app-setup-policies. However, some parts within the Teams app have been adjusted to reduce demand as the service scales up. I don’t know if this is one of the affected parts. Things aren’t working in my tenant either. I’ll ask Microsoft.
Woout, We’ve opened a support request to get this fixed. Currently that has the attention of the product group itself, but still no fix
Hello! for some unknown reason the assignments option disappeared. How can I reset it?
First, sign-out and sign back in again. It could be a transient error. Second, check if there’s a software update available for the Teams client. If those steps don’t work, file a support incident with Microsoft.
Is it possible to PIN an App after installation, so that the user doesn’t have to do it manually?
How do you mean? Teams will read the pinned information when a client starts (and I believe from time to time thereafter) and pick up changes. Maybe I don’t understand the question.