Is Nascent Flash bugged?

I was dueling with my friends while we were in a party of 3 for the first time at the Wolves' Den Pier and sometimes I could activate Nascent Flash but other times it just kept saying "Invalid target".

The tooltip seems to suggest I can only use it on party members but I did manage to use it atleast twice. One of those times was just before or just as the duel counted down to zero.

I can't figure it out and it is driving me crazy.

Duels prevent you to apply buffs from inside outwards and vice versa. The time before counter hits 0 is not part of the duel.

Nascent Flash in PVP always needs a target, but duels prevent you from interacting with anyone but your opponent.