Moved to 532 subforum.
The 640 and 640 XL have less display memory than is optimal, resulting in the same thing you are seeing. It appears the low-cost 532 also has that limitation, and we cannot force more things to work.
If your glance settings do indeed have the option to display the background app, disregard what I just said, but the fact you're asking means that it probably isn't there.
The options then are to get a device that is capable of displaying the extra info such as the Lumia 830, 820, 920, 620...