"Next waypoint" datafield not displaying anything

Hello everyone,

I'm running a mountain trail in one month where I need to set waypoints (because of time barriers I want to know how far and how above is the next waypoint).

I have pretty much figured out how to set these in the GPX course and transfer it on my watch, but while testing I have noticed that sometimes the "next waypoint" datafield doesn't show anything... Which makes is kinda pointless because then how to be sure that the "distance to next" and "V distance to next" relate to the good place ?

Has anyone had this issue before, and would have a clue what is wrong ?

Thanks a lot !