I have Spark Pixels 4 on my cube and version 0.2.9 of the Android app.
When I start the app, I get a message saying that my Photon is online but not running the Spark Pixels firmware. If I click continue anyway, I get a box that says an error was encountered, make sure the device is online and loaded with the firmware and a status code of 401. The web version works fine. Also, it works fine from CLI.
On the hypothesis that was an HTTP 401, I logged out and logged back in. Success!
The fact that it seemed to be able to see the device at all was very misleading.
I'm posting this here in case anyone else encounters this or in case there's some improvement that can be made.