Why aren't contour lines showing up on my Fenix 6 sapphire NA TOPO map?

Hey, have you tried uploading OpenTopoMaps? I use OTM with additional contour lines overlay and it's fairly accurate.

Make sure the contour map itself is turned on, it is possible the contour lines are not in the topo map file but a separate map file, could be the DEM map. What you should do it enable all maps and check that and then work things out from there. If you have no map file with embedded conttours that is enabled they cannot shot. Also contours display could be affected by the details settings for your maps. Contours are simply another piece of data stored in the map file and the settings are to show them or not, just like a road. Shading is another thing completely and is computed on the watch based on elevation data but not contours. 

Do you live in the U.S?... you should have a contours map on the watch as standard... or imbedded contours within a map... 

If you live in Europe like me..(or other places) . then there are no contour maps as standard on the watch...

But Garmin have allowed us to upload any maps we choose in the right format..(more detailed maps with built in contours ) .. And it's really simple to add a transparent contours map from different third part sites to overlay on any other maps... 

You can get a transparent contour map from the link below if you want... 

garmin.openstreetmap.nl/

Make sure the "Draw Contours" option is turned on (under Map settings).

Three years later.. this just helped me.  Thanke!