Did some major brushing of IPC to understand better what is going on. Finally, I found the culprit: a missing occurrence check! In the process, I also expanded suballoc by an explicit rc parameter through the RC phase. While this in the current version is not strictly needed, it opens the door to further improve / refine our suballoc to support a generator-instance specific RC in order to avoid copying in shared scenarios. See details on this in issue 2288.