hi sidiabale, take a look at this topic: https://stackoverflow.com/questions/49885112/proguard-server-build-error-codename-one/49891191?noredirect=1#comment86961762_49891191
having issues with the Proguard, the cn1 server can't build with Proguard enable, seems it's something related with parse4cn1, tried many and many attempts to fix it as you can see in the commentaries, looking forward for a solution.