I opened the chest and nothing happened, no itens, no new quest chain, no messages, nothing. Why? Is it normal or bug?
Speaking of that secret location…How did you get to reach the separated place in 4F?
I also want to know 
there’s a portal in Tiltas valley, after a quest it should lead you there.
Means Tiltas Valley or the Royal Mausoleum Chapel Construction thing… Well, I’ll go check that ^^ Thanks for the tip 
I just had this problem… did anyone find a solution???