You can use the onX Offroad App on your mobile device to show or hide Markups (Waypoints, Lines, Shapes, and Tracks) on your Android Auto or Apple Carplay in-dash unit.
Open the onX Offroad App on your mobile device, and tap the My Content Button at the bottom of the screen.
Tap "All Content."
Turn off "Only list content currently on the map"
If a Markup still isn't showing on your map, tap the three dots next to the Markup in the My Content menu and tap "Show on map."