Android app does not connect to Firebase
I had the exact same issue. I built successfully but got the same message when hitting the 'Connect to Firebase' button via Assistant.
It turned out that I had a warning that I had to fix to get it to work.
"Configuration on demand is an incubating feature. WARNING: Configuration 'compile' is obsolete and has been replaced with 'implementation' and 'api'. It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html"
I just had to replace my 'compile's with 'api' and then it worked. I'd suggest looking into fixing warnings if you have any even though your build is successful.
I suspect that the gzips in your project might be the culprits. Search it up within your project folder and delete them, let gradle re-sync it for you.
Possible alternative solutions: https://github.com/socketio/engine.io-client-java/issues/13 https://github.com/ACRA/acra/issues/159
I tried a lot of ways, but the simplest way is updated com.google.gms:google-services
from 3.1.1 to 3.2.0