My senior team has mentally checked out

Half my senior team has stopped challenging anything. They deliver what is asked, hit their targets, and say nothing in meetings. Eighteen months ago these were the people who would argue with me, push back on bad ideas, and stay late because they cared. Now it is just compliance. I cannot figure out what changed or how to get them back without sounding like I am running an engagement programme.

Background

We went through a restructure last year — no redundancies but reporting lines changed and two senior roles were made redundant at director level. I think this spooked people but nobody will say so directly.

Already tried

Team away day (felt hollow). One-to-ones where everyone says things are fine. Engagement survey that scored 7.2/10 and told me nothing useful.