Why?

Why do you insist on ruining the basic function of the site with each update? Why can't I group select drawings on the DL layer? C&P DL lines makes doing repetitive work so much easier but now I can't select a two-line X for a tree to copy and paste to ALL the other trees.

I just tried this and it seems to work for me.  Are you using Legacy Dynamic Lighting or Updated Dynamic Lighting?  These are my repro steps: Using the Pen/Line Tool, draw a line. Draw a second line crossing it. With the selection tool, draw a box over both, selecting them. Hit the copy shortcut on the keyboard Click on the map Hit the paste shortcut on the keyboard Observe the newly created lines. Does that vary from what you're doing?

Yeah, I tried all those things. One thing I didn't try was selecting a huge section of the map. The X takes up 1/10 of a square but if I select 4+ squares, for some reason it selects it but doesn't when it's just one square selected.

Hi taibhsear,  Selecting tiny drawn objects has always been a problem in Roll20. Zooming in usually helps, as does grabbing a large area (larger than expected as you discovered). 

Also, if you have paths (lines, squares, circles, etc) overlapping in the same area, holding "alt" while dragging a selection rectangle will constrain the selection to only affect paths.

Selecting can be tricky, especially lines from the drawing tool (as opposed to Tokens or Maps which are graphics objects) I find that adjusting my Zoom one way (OR the other way) can help. Just zoom in a bit and try selecting again.  I vary between point-click to select it (hold SHIFT to keep point-clicking more to add to the selection), versus click-drag to select. Both (can) work.  I have a theory (not sure if true) that selecting near the starting-point of a Drawing Tool line is more reliable than selecting a distant point on a large long line.  But anyway, the tips everyone else said above me, are good.