When I wake up every morning, I check to see if there are any app updates, and there usually are. I tap on the App Store icon, and before tapping "Update All", I pull the screen down with my finger and release. This updates the screen and there are usually a couple more Apps added to the update.
So you might want to try that. Tap the App Store icon, and then pull the screen down with your finger and release. That might show you the exact number of Apps that have an update.