We keep having this issue as well. I undo our VMAN integration, redo it and it's fixed for a bit, but then it happens again.
I know it's been a while, but did you ever find a solution to this?
I don't even understand why breaking the VMAN integration and redoing it helps since Hardware Health is polled by Orion itself. VMAN shouldn't have anything to do with it...
It turned out that we need SAM to be able to do this. We had installed the SAM trial a while back and then removed it, but somehow this functionality remained through a few upgrades. I guess that the NPM 12 upgrade just 'fixed' the problem.