If using a key command to activate horizontal cursor, it won’t show up on the relative tool (pencil tool) until you switch to another tool and then switch back.
You mean Preferences > Tools - Show Horizontal Cross-Hair Cursor Line, right?
Yes, I can confirm. The cursor has to be redrawn. It also appears, if you move your mouse over the Track list or the Left or bottom area of the Project window, or the Ruler. The Cursor just need to be redrawn.