Apps don't download/update after MacOS update to Mojave!

I updated my macs (MacBook Pro and a new MacBook) to Mojave a few days ago. App store (on MacBook) shows that updates are available for iWork and other apps. When I click on update nothing happens! I tried signing out and in again and restarting but it did not work. On MacBook Pro there is a notification sign on the App Store icon showing that update for an app is available, but it shows nothing on Update page when I open App Store!

Could anyone please help?

ps: I checked to see if there are other copies of the App Store on my macs, there was only one.