Apologies but I cannot answer your question directly, but I can tell you what I do know.
I noticed whilst doing story quests that I was getting around 4k xp for a 5mins quest..,,and it takes 300xp to lvl as a lvl1.
So I picked up say like a lvl16 story quest as Paladin, did the quest and attempted to hand it in
as a lvl1 Arcanist. I was interested to see that a red cross appeared above the NPC when i changed jobs, so I could not hand it in.
This suggests they "lock" the quest to the job that the quest was started with.
I think it's simpler than that. There is a level requirement to finish
a quest as well as a level requirement to activate
the quest. I've noticed during both Phase 3 and Phase 4 that when I traveled to Gridania to unlock and level CNJ that there were certain quests in the Central Shroud that I could activate before level 10 (I was level 8 at the time, I believe). But when I completed the quest objectives, I saw the red cross on the NPC like you saw. I was CNJ the whole time. When I finally hit level 10, the red cross changed to the usual quest completed icon and I was able to finish the quest.
I'm betting that the quest you were trying to complete has a minimum level requirement for finishing, just like the quests I was doing. That would explain why you couldn't finish it as a lvl 1 class.
I'm not sure why some quests would have a higher minimum level to finish the quest than it requires for flagging the quest. I wonder if it's a bug, and that the two level requirements are supposed to be the same (which would make more sense).
Lyonheart, like Eorzia, will be reborn in FFXIV!
FFXI veteran (Lyonheart and Lakiskline of Lakshmi)
1/467 on signed HQ Weskit!!!