Make sure you have configured Group Policy correctly:
To show private store only in Microsoft Store app
Type gpedit in the search bar, and then select Edit group policy (Control panel) to find and start Group Policy Editor.
In the console tree of the snap-in, go to User Configuration or Computer Configuration > Administrative Templates > Windows Components, and then click Store.
Right-click Only display the private store within the Microsoft Store app in the right pane, and click Edit.
This opens the Only display the private store within the Microsoft Store app policy settings.
On the Only display the private store within the Microsoft Store app setting page, click Enabled, and then click OK.