Just cleared the Naruna Hot Springs dungeon on normal mode and didn’t get the reward chest. Same thing happened to a friend aswell. I’m guessing the boss drops the chest but because when he dies you instantly get put into a cutscene then a different zone you don’t get the chance to pick it up. Feels bad to lose out on those mats.
Server: Thirain
Ingame Name: Clyve
Friend’s Ingame Name: Ex
Did it on hard, didnt get the reward chest either.
Region: EU Central
Server: Sirius
Ingame Name: Omegajuice
Did it on hard, Didn’t get the reward either.
Region: EU Central
Server: Trixion
Ingame Name: Makrah
Tried it on both Normal and Hard, had no reward.
Region: NA West
Server: Valtan
Ingane Name: Yunoh
Just did this as well with no rewards on hard, so on Normal I waited until the boss took us back to original arena and I got the rewards. Kinda comical tbh
Region: NA East
Server: Una
IGN: Bottom
Same here
Region : EUC
Server : Kadan
IGN : Siltadriss
Same here
Region : US East
Server : Valtan
IGN : Spankky
Same here
Region: US East
Server: Regulus
IGN: Trace
Same here
Region: US East
Server: Una
IGN: Lessen
Completed the dungeon on Hard Mode. Did not receive the completion rewards.
Region: US East
Server: Una
IGN: Pleasecomplain
Same happened to me.
US West
Enviska
Brolyy
Happened to me as well. Did we find a reason yet?
US East
Regulus
Ploogy
same here:
I have cleared normal and hard difficulty still nothing
Region : EU Central
Server : Neria
IGN : Jedynak
Still no fix ? just did it and no reward
EU Central
Trixion
Griska
Normal Completion. No Reward. Checked my bags for a good 5 minutes thinking I was crazy
Region: US East
Server: Karta
Ingame Name: Juicies
Same, didn’t get any reward for completing it on normal mode 
Region: EU Central
Server: Thirain
Name: Zpray
Same issue . Normal. Hot Springs. On alt.
Region : US West
Server : Valtan
Ingame Character : Averluna
Same issue . Normal and Hard mode.
Region : NA East
Server : Avesta
Ingame Character : Adoraa
Same here
Region : US East
Server : Elzowin
IGN : Vermag
Same here, happened on my main and alt account on hardmode
Region: NA West
Server: Galatur
In-game name(s): Penguardo and Penguardi