TFS 2015 installed widget can't be added

We want to customize one of our on premise TFS 2015 Update 2.1 dashboards. We installed a widget from the marketplace (this one).

I can see it when I go to the "Manage extensions" page. If I try to reinstall it for the team I want, it says: "The extension is already installed for this collection: {My Team here}. Select another collection to proceed.", so it is definitely installed.

However we can't add it to the dashboard, it doesn't appear in the "Add widget" popup.

Am I missing anything here to make it work ?

Solution

I just tested installing this widget on my TFS 2015.3, it shows as expected. I'd like to suggest you upgrade your TFS to Update 3 and have another try.