My problem is similar but different. I too get a notification that there are apps available to be updated, but the list is completely blank (doesn't say that they're all up to date). It's been a week since it's updated, and I know for a fact that there are even more apps to be updated than the badge tells me. It seems that the app store has stopped refreshing all together, and won't download any new updates. This has happened a couple weeks before too and restarting fixed it. If I restart I'm sure it will fix itself, but it's a pain in the *** (due to another ios 7 bug which causes my iphone to crash each time I restart, and it can take multiple restarts before I can use the phone again).
i'm having a similar problem but mine is that the App Updates are showing up in my iPhone5/iOS7 and iPad3/iOS6 but not showing in my MBAir/iTunes11. tried updating to the latest iTunes but still nothing. this started only yesterday... i hope it is just a bug with Apple servers and would solve itself soon.
Eventually, my problem did correct itself after a couple weeks. The interim fix was to scroll through the "purchased" apps and manaually update apps that I had installed. Time-consuming, but it worked. I believe the issue was simply a matter of the information not displaying correctly, which Apple fixes on the back end with their store coding.