Naxx Teleport to Sapphiron Bug
Dec 4, 2020
This is currently working as intended. Once you clear all 4 wings, the teleporter to Frostwyrm Lair activates and once you take that teleport, its a one-way trip. This matches the behavior in Original WoW.
It’s definitely advisable that if you want to grab any frozen runes on the walls, or do any other exploration of the dungeon after clearing each wing, you should do that before entering Frostwyrm Lair.
I’ve gone ahead and added this to the Not A Bug list… for now.