Hi Kevin,
yes, this is unfortunately a new bug discovered in MOE 1.2: https://github.com/multi-os-engine/multi-os-engine/issues/68
Here are more infos about it in another topic: Exporting a distribution IPA with XCode 8
A workaround should be to add --no-daemon to gradle invocation in the custom build phase script in the Xcode project.
Please make sure that all previously started Gradle daemons are stopped / killed prior to trying the --no-daemon option.
The issue was not triggered for us previously, because we are using a 2 step build, like described by Paul in the other topic: we first build with gradlew moeIpaBuild, then xcodebuild archive is used with MOE_GRADLE_EXTERNAL_BUILD set.
Best Regards,
Gergely