The Chrome browsers have no special extensions loaded (other than the default Google Docs extensions bundled with the browser).
It's getting weirder still. On Chrome/Win10, the bug disappeared when I opened the built-in Developer Tools. It seems to have disappeared permanently for that combination of browser/OS.
So I tried the same thing with Chrome/macOS. In a tab with the Developer Tools open, the bug is gone; all elements highlight correctly. But at the same time, in another tab of the same Chrome window, the bug is still there.
The Chrome browsers have no special extensions loaded (other than the default Google Docs extensions bundled with the browser).
It's getting weirder still. On Chrome/Win10, the bug disappeared when I opened the built-in Developer Tools. It seems to have disappeared permanently for that combination of browser/OS.
So I tried the same thing with Chrome/macOS. In a tab with the Developer Tools open, the bug is gone; all elements highlight correctly. But at the same time, in another tab of the same Chrome window, the bug is still there.