Okay - so I've got those panes showing now: both Markers and Scale Bars.
But please look at the attached screen grab. You will see that I have placed 2 markers on the shaded version of my ballerina model. On one of her feet. So far so good.
I couldn't select these markers in the Model viewport as I think I should be able to, but I could select them both in the Workspace pane. I did so and created a Scale Bar from these 2 markers.
No scale bar showed up in the Model viewport but a scale bar showed up in both the Workspace pane and the Scale Bars pane, so I'll go with that. Don't know why it didn't show up in the Model viewport. And I'm talking about a line between the 2 markers. That line didn't show.
You'll notice that I have no option to insert a measurement in the Scale Bars pane. In fact, click as I might, I can't enter any data in any columns at all in the Scale Bars pane. I would like to enter a value in the "Distance est (m)" column but no matter where or how I click, no window opens up where I can enter a number. Interestingly enough, when I double-click in the "Accuracy (m)" column, a window does open up. But I don't know what to even put in that window.
And so I'm bugged again. And seeing as I'm in California and you're in Europe, I won't have an answer from you for some hours.
So I'll keep trying and hunting an punching around and tearing my hair out...
Jon