If you're working with langify across multiple stores, note that you can only be logged into one store at a time.
Even if you open the langify app in a second store, your session remains connected to the first store — you'll see that store's name displayed in the upper-right corner.
To switch between stores, log out of langify before opening it in another store. You can do this by clicking the circular icon in the upper-right corner:

Then choose Logout:

Langify doesn't always provide visual feedback when logging out. After clicking Logout, you can usually just close the tab. When you open langify again via your other store, check the store name in the upper-right corner to confirm the logout was successful.