I will mention the ways I have had problems with tasking. You may have checked these already.
1) not having my file with the predefined task set as Active. It must be the active file and not just have a checkmark.
2) active waypoint file not containing the turnpoints needed for the task.
If neither of those are the problem, then I would try to get a known good waypoint file to add and verify that when Active, you can’t find waypoints. That might eliminate some weird file format error.
With new tools like the TurnpointManager site coming online, there is always a possibility that a file isn’t compatible for some unexpected reason as part of the cup export process.
Good luck,
Morgan