By any chance do you have the "testOnly" attribute set on the application tag in your Android app manifest?
If that attribute is set, then the apk will only be installable using adb. You can pass the -t parameter to the adb install command to install a testOnly application. ("adb install -t yourapp.apk") Alternatively, you can also use ML hub (or the play button in Android Studio) to install applications with the testOnly flag. ML hub will ultimately shell out to adb, so using it to deploy and install works as well.