In the latest version of LR on mac, I find that if I click on the detail picker tool (top left corner of the detail panel) to try to pick a location to look at the detail, it doesn't let me do so. The cursor stays as the zoom tool so I am never able to pick a spot to look at the detail. Is this a known bug??
You are seeing a known bug that Adobe is working on and will probably be fixed with the next version.
If you can't wait you can roll back to 6.10.: https://www.lightroomqueen.com/roll-back-update-previous/