Can't Select Drawing

Sometimes, lines I draw for UDL stop being selectable. Even if I delete everything around them, select a wide swath, change my zoom, whatever.

Any idea how to fix it?

I just finished making a big map and I don't want to have to just start over.

Sorry to hear that, Essen. I'm usually able to select drawing objects, including lines, if I zoom way in; annoying that that selecting while zoomed in is not working for you.

Drawing objects are harder to select than they need to be, in general. I'm hoping some future accessibility-focused update will help with that, but, in the meantime, here are my suggestions for drawing DL lines on future maps. Sadly, I don't have great suggestions for your current map.

1. Avoid the thinnest line weight, when you can.

2. When you need to use thin lines, make little tails on dynamic lighting line segments, to act as handles to help you select the segment. (Those handles will block vision and movement, like anything else, so you have to be a bit clever about where you place them. So it's not my favorite workaround, but it's better than nothing.)

Edit: Thanks for the reminder, Jim R.! I forgot that it's now possible to use the Freehand tool on the Dynamic Lighting layer. Best avoid that particular trap altogether.

Weirdly, selecting a square to the left of the line lets me select it, and the selection is longer than the line itself. 
Something is obviously wrong with the line somehow.

Are your drawn lines Freehand or Polygon/Line? Try to stick with Polygon/Line.