Default [Q] cannot find app after installing using adb

Hello, I am trying to install app that is not letting me install. If I try to install from the sd card, I get application not installed.

So I tried using adb. Here's the command I used

cd C:\android\sdk\platform-tools
adb devices
adb root
adb remount
adb push app.apk /system/app
adb remount
adb reboot

I can see the app in system/app, but I cannot see it anywhere else. If I try to install it I get application not installed.
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