Firebase Test Lab: "Application Not Installed"

I'm trying to run my app UI tests in Firebase test lab. After uploading my base APK and test APK, selecting phones, and starting the tests, the test matrix results just show "Application Not Installed" for all phones. When I click on an individual result, it just says "Application failed to install".

This same UI test runs fine in emulator and on my physical hardware. Why would it fail to install? Is there any way to get debugging or logs to see what the problem is?