I'm a pretty well versed instructor in Word. This 'comment' is about configuring a Vertical Bar tab in Word. To be practical the bar tab must be in the left margin. In WD 2010 it was easy to do that. Set the current Tab to Bar then click anywhere in the ruler to place the tab. Then drag it along the ruler into the left margin. That's all that was required.
Now!!!!! In 2016 it doesn't work. Set the current Tab to Bar and try whatever you can think of, it will not move in the left margin.
Only way to do this is to deal with the Tabs dialog box ... within the Paragraph dialog box. Then after quite a few steps, to set it up.
And once it is setup properly if you try to drag it a tad along the ruler it jumps on the left margin and will stay there! Impossible to move it.
I use the Vertical Bar tab a lot to highlight that a paragraph is important or may need some adjustments at a later time (No Track Changes here!).
What I'd like it to have is this feature work like it did in 2010, perfectly well!!!
For the moment I revert to using a simple style using the Normal style but with the Bar tab. But again if I touch it with my mouse, Bang! on the left margin.
Kind of weird that I paid hundreds of dollars to upgrade to 2016 and I find things that are lost!
I haven't used the bar tab that way, but messed with it a bit based on your description. Indeed, it doesn't want to allow tab sets in the margin area. But I also have a work around for you.
Move the left indent to the edge of the page, set the tab as you usually do in the text area, then drag it to the desired point in the margin area. Now move your left indent marker back to its original position.
I know it's an extra step and not perfect, but it does save you from having to deep dive into the dialog boxes.