I have the same or similar issue.
I am using react-native-config and need to set th ENVFILE property.
Locally, i can can run
On bitrise, I create a script to use envman and set the variable. I also created another script to test wether it was property set (echo $ENVFILE). Then I run Android Build (which i think essentially runs assemblyRelease). However, the generated apk is still not using my staging configs, which is what ENVFILE is supposed to do.
Any help is greatly appreciated, thanks!