Can't add a private app to devices
I'm being very confused when trying to add a private app into the Stix EMM, and I'm not sure where the problem lies, so I'm asking here!
I successfully loaded it in:

But when I then click on that and then try to click Select app... nothing happens. Nothing on screen, nothing in the dev console, no network traffic... Nothing.

And so I can't add this app to my devices. And I'm entirely lost as to what's going on.
Is this a Stix thing? Or an Android Enterprise thing?