EPERM: operación no permitida, lstat gradle
Workaround 1:
cd into <APP DIR>/android and run ./gradlew clean
Execute react-native run-android
Seems to work every time but takes forever since everything must be rebuilt after the clean. Which leads us to
Workaround 2:
Execute react-native run-android
As soon as React Packager opens, close it
Wait for react-native run-android to complete giving you the BUILD SUCCESSFUL message.
Then run react-native start to start the React Packager
Reload the emulator (Double tap the R key)
This workaround is usually faster than the clean/rebuild way for me, so while eagerly waiting for a permanent fix to this problem I'll just stick to workaround 2 as long as it does the trick.