It’s a common misconception that you need to use the "Offline Maps” tool to view maps after you have cached them. The Offline Maps tool is only designed to help you choose what maps you want to cache. Once cached, the maps will be available from any map within the application while out of network.
If you select My Map Packs from Offline Maps, and then choose “View” you will be shown the area that the maps were cached in. This screen won’t let you zoom in/out, and won’t allow you to use see all of your trip content. Please select Maps to view and zoom your cached maps.