I have a very odd issue when attempting to install Sales Analytics for Dynamics 365 Sales. After registering and installing the app, Process Analytics for Dynamics 365 is the app that actually gets installed. I have nothing else going on in my PowerBI instance, so this isn't getting mixed up on the user side. It's an app installation issue. I've been able to recreate the issue each time on reinstallation.
You said that there is nothing else going on in your Power BI instance after you installing the app , what it refers to ? After you installing the app , can you see it in your Apps pane ? Under what circumstances do you need to reinstall the app every time ?