Hi Richard; jsut fyi, in case it is something systematic:

I recently updated something in openstreetmap. That is meanwhile also reflected in your maps - but not anymore if you zoom in.
(So, it is hard to use that path, as you can not see it...)
These are the coordinates of the marker - I am talking about the red cycle path leading to that marker:
Visible when zoomed out:

Not visible when zoomed in:

(On openstreetmap, it is visible on all zomm steps)