Not the parent, but I've seen it and it's hard to say, 5.5 was being stupidly proactive in monitoring a long-running process in a sub-agent to the point of chowing tokens by continually monitoring.

I queried it and was told that sub-agents can't run processes a blocking fashion, I'm not sure the harness changed, or the model was handling it differently, but it require some changes to skills to prompt around it.

Previously after the subagent finished it sent a message to wake up the orchestrator agent. I hope they haven't changed this..