Elevation profile issue

I’ve just finished Caen-Lyon-Biarritz with the assistance of cycle.travel routing - fantastic !! However my Garmin (explore) failed to receive the elevation data with each 75mile (ish) section. Previously there’s been no problem. The sections were created on line (Mac /safari) and transferred directly to the ‘New files’ folder on the Garmin. Any idea what’s causing this ?  Thanks. Tom