I could not pin the exact portal from the description alone. Which quest or which map is this on (the pitch-dark map with the hidden clickable for the document)? With the map name or quest name I can fix the portal target directly.

Thanks Kiji, your screenshot answered our question: this is Bedin's quest in Magatia, "An Incident, and the Missing Alchemist". In the original, while you're on this quest the portal in Lab - Area B-3 takes you to a pitch-dark copy of the lab where the Secret Document is hidden; everyone else goes to the regular Area A-3 with the monsters. Ours lost that quest check and the dark room is missing, so right now the quest (and the ones after it) can't be finished. The fix is being made now, and we'll post here when it's in.

This is fixed and live now. While you're on "An Incident, and the Missing Alchemist", the door in Lab - Area B-3 takes you into the pitch-dark lab. Search Alcando's Cabinet there to get the Secret Document, then bring it back to Bedin. If you don't have the quest, the door still leads to Area A-3 as normal. Carson's Experiment and Parwen's Lab can be done after it again. Refresh the game once to get the update, and reply here if anything along the way doesn't work.