Publishing externally (bintray/mavencentral) has some wrinkles. Also depends on gradle version. The metadata for gradle 4.7 is 0.3 and for 4.10 is 0.4, and they are incompatible. Most of the JetBrains libraries are 4.7, but hopefully moving towards 4.10 soon as new android studio wants that. I just spent the good part of a flight wrestling with kotlinx.coroutines trying to publish on 4.10