ITunes 12.2.1.16 but cant access app store but can access Music store

I have upgraded to latest iTunes 12.2.1.16 but although I can see Music store I do not see the app store when trying to upgrade ipad or iphone apps using my mac within itunes. Have reset password but app store screen remains blank? I have apps in my itunes that need updating but it won't accept the password even though it knows it is right as I can log into my account. Any ideas? My app store works fine on my Mac Pro and I can. update apps using my ipad or iphone just not via itunes app on mac.