Hello!  New to the forum, and mostly new to Inkscape except for trodding my way through a few basic tasks over the years.  The little past experience I've had was in 0.92, but now I'm using 1.2 (on macOS 11.6.)  I tried searching the general Internet and this forum, but didn't have any luck finding a solution, but perhaps my google fu is not up to par.  And, I did try clearing my preferences and restarting in case an old setting was cached.

I'm trying to draw a flow chart by following a demo, by following along and using a blank canvas.  I'm getting hung on on a part that is drawing a line with a few segments, as in this video (at the 10:05 time mark.)  I've been able to get through everything up to this point, but when I follow the same steps, instead of a couple of line segments, I get in a filled in shape.

Left: Here is what the video demo shows.  Right: Here is what I get.

With the changes in the new default theme, I'm not positive, but it looks like the video author is using the Pen (B) tool, selecting paraxial segments button, and using shape None.  Is there another setting that I'm overlooking?  How can I mimic the original behavior?  If it's not possible anymore in the new version, can you provide more background on why, and what the new way to do this would be?  The description of the Pen tool at https://inkscape-manuals.readthedocs.io/en/latest/pen-tool.html shows only one example, but it's a fully enclosed object.  If that's true, then is that new behavior?

Finally, if there's just an all-around better way to do this, please share.  It would be nice if it could still be a single line with multiple segments, one that can snap to grid/keep a right angle, etc, as would be expected on a technical drawing.

The tool may have a fill color assigned. Before drawing with the tool, I'd click on the tool to select it, then click on the red x at the left-end of the palette to remove the fill from the tool. 

Fill and stroke of a tool are indicated in the far end of the tool controls.

Thank you!  That is exactly what I needed to do.  I'll elaborate on your instructions for anybody else who comes across this in the future.

The palette with the red X is all along the bottom of the window on my computer.  The screenshot below is what it looks like.  (Screenshot taken after I clicked it, so I think Fill was the color I was seeing, which was solid black.)

Then, I used the Fill and Stroke settings box to change the stroke, because the lines didn't appear before.  This can be opened with Shift-Cmd-F on macOS; menu Object -> Fill and Stroke...

I clicked the first, solid box - Flat color - et voila, the lines appeared!

Another important detail I didn't pick up on before making these changes are the indicator on the right side of the top toolbar, showing the fill and stroke of the Pen (which only shows while the Pen tool is currently active.)  This changed with the settings in the Fill and Stroke panel, and looks like it contains the same information in the palette bar.

I just created an account to thank you for posting this! It explained my issue step by step - thank you! :)