A solution that’s worked for me is to bring up the route in the app so it’s ready to use as soon as I hit the green Start button. I’ll do this at home or wherever I have cell service. This seems to queue the route in buffer mode so it will work properly after I lose service. I’ve done this many times at Hammond Hill without issue.
I use the iOS version, but based on your screen shots it looks like this aspect works the same way for Android. For this year’s courses I think Hammond is the only one where cell service is consistently lacking for me, but it should work the same way on any of them.
It’s probably too late now, but I’ve also shared downloadable .gpx files for the 5 trail courses in a separate post. You can load these to your watch or possibly some other phone app. Shared .gpx files for 2024 FLRC Challenge courses