Hello,
In the Advanced sample project, open the level blueprint and in the tick function you will find all the GetMarker nodes. Each GetMarker node has a visibility pin. If the marker is tracked the visbility is true.
You can use this value with a branch node to hide / unhide the menu widget. (SetVisibility) In case you have more than one GetMarker nodes at the beginning of the tick function set a variable to false and only set it true if any of the GetMarker nodes visbility is true, then test against this variable.