Thanks, both, for your inputs.
How odd - I have exactly the same.
Our Mac admins are putting a new build together, so with the forthcoming move to 10.0.x and the Mac 10.0.3 client being able to run native on M1, that is the agent we have selected.
The relevance for the property that fails to report is
if ( exists true whose (if true then exists main processor else false ) ) then ((significant digits 2 of (speed of main processor / mhz)) as string & " MHz " & family name of main processor as string) else ""
The test M1 Mac isn’t on-line now (and would be on the wrong end of an off-prem link anyway) so I can’t get answers out of it now, but will create an analysis for it with the relevance broken down into its constituent parts, but from the results already posted by @atlauren it looks to be the ‘speed of main processor’ clause.
I’ll post the results when I get them, but that won’t be before Tuesday.
The property in question ‘CPU’ is in the site ‘Reserved’ and I can’t edit it. Perhaps the property is fixed once we step up to 10.0.x (I can’t confirm that because our pre-prod rig is back down at 9.5.13 pending another upgrade dress-rehearsal run).