How do I manually install an app in iTunes 12.7? I foolishly installed iTunes 12.7, and now find that I am unable to install a development/QA version of my company's app for testing.  After downloading the IPA, I am following the steps found on Apple's support page, under "Manually add items from your computer."  

There, I'm told to drag the IPA file to the iTunes sidebar, like so:


  


But when I do exactly that, it tries to create a shortcut, and fails (the section of the sidebar blinks several times):


  


This is in iTunes 12.7, to an iPad mini 4, iOS 10.3.3.  Manual management is enabled:
Have you tried the Apple Configurator 2?

I just read about it here, but haven't actually tried it myself:
How do I download an iOS App (IPA) file to my Mac after iTunes 12.7 update?

Here's a description from the above link:
http://krypted.com/apple-configurator/upgrade-devices-and-apps-using-apple-configurator-2/