pmaxjenkins

I've been having exactly the same issue and after reading this found another way to solve it. It appears that the App Store didn't recognise that Photo or Designer were installed (They both were) I went to purchased Tab on the AppStore and noticed that next to Photo and Designer it was showing an INSTALL button. I clicked the install button, App Store did its thing and the latest version was installed.

I solved it for myself. I wasn't seeing the Welcome Screen as I had turned it off. In the Mac version select the Help > Welcome option and the screen showed with the offers Hope this helps others.