To all having the issue ralated to iPad AppStore Update blank screen.
This is what worked for me. I tried everything on this post and almost nothing worked for me. When you have no updates you should get the "All Apps are Up to Date" screen, if you are still having a blank screen the problem is not fixed. I am saying this because I was able to update my apps, when I was experiencing this issue, by connecting my iPad to my Mac Mini computer, then connect my iPad to my computer and update the apps in iTunes using my computer and then synch the iPad with iTunes on my computer. The small update sign on the iPad AppStore icon dissapeard when the synch process finished. However the update screen still showed a blank after I completed this process.
So I contacted Apple and they recommended to Sign Out my Apple ID account from the settings screen and reboot my iPad, then sign in again. This method did not work for me.
Solution:
Following the same logic, I deleted my iCloud account from my iPad's Mails, Contacts, Calendars Settings. Then I added the iCloud account again. During the process the iPad will ask you if you want to retain your contacts, calendars and reminders on your iPad. I answered yes. Then when you add your iCloud account again it will ask if you want to merge the contained information and I answered yes.
Make sure you close the AppStore apps by double click the home button and delete the app from the recently ran apps bar at the bottom of the screen before you run the AppStore again.
Then I opened the AppStore Update page and it worked fine. Not sure for how long it will work since I believe the problem is an intermitent issue with Apple Servers.
I hope this works for you.