Cordova UWP installs on Desktop, but not Mobile

I have an Ionic 3 Cordova application where I have built it for the Windows UWP platform. I have tested this in office by side loading onto both my desktop, and onto a Surface tablet.

I've submitted to the store, and check both Windows 10 and Windows Mobile as shown below...

I selected the Mobile thinking this would cover the tablet option. I don't have an actual Windows Phone to test on, but just assumed this would be the same as the tablet.

After submitting to the store, I havethe following reported back..

Installs on: Desktop

Does not install on: Mobile

Tested Devices: Windows 10 Desktop, Windows 10 Mobile

In my config.xml, I have only the following set

 <preference name="windows-target-version" value="10.0" />

I have built for just x86, but I thought the Universal meant it would install on any Windows 10 device? Any ideas on what I may need to do?

Windows 10 Mobile runs only on ARM processors so you'll have to add the ARM architecture to the outputting package.

Speaking about architectures.. Why don't you add x64?