Problem with macOS Safari Web Inspector?

Question

safari

Have you ever had this - you open the web inspector in Safari, you start, for example, changing the css properties of some element and you notice that nothing changes, and sometimes the syntax highlighting becomes instead of the usual (red and black) gray, as if inactive. By experience, I already quickly solve this moment by clicking on any neighboring html element in the "Elements" tab and then clicking on the previously edited element ?

Is this a Safari bug? The problem is observed with High Sierra, now it costs Big Sur