I had to go to the Shiratake Temple for my school quest to get Triton. After finishing the quest, I wanted to go through again for drops. I couldn't re-enter the dungeon. The sigil was active (it was glowing), but when I approached it, I couldn't interact with it to enter.
I haven't reached the point in the storyline quests to access the dungeon so perhaps that is the problem but it seems odd to not be allowed to access previously accessible content.
