From VG247: “Heres how to build to the sky and Search Floating Lightning Bolts high up around the map.
To make sure the Floating Lightning Bolts or as youd say in Spanish, Rayos Flotantes count towards your challenge progress, you cant just glide through them. You have to land and then hold a button or key to search them properly.”
Source: N4G PC Fortnite: Search Floating Lightning Bolts – Every Floating Lightning Bolt location