When I execute the command
(lldb) po app.debugDescription
The view hierarchy will refresh when you interact with the app (since it's reasonable to expect that the app's state doesn't change unless the user interacts with it).
To get a fresh view hierarchy, you can either tap on the app:
app.tap() and then print the debug description, or you could create a new instance of
XCUIApplication and use that instead of the existing
app property which has the cached view hierarchy. The new instance should show a fresh view hierarchy.