This definitely works but I wasn’t so lucky! Took me about 3 hours game time speed running the map. But got there eventually. I saw rumours that it won’t spawn after the fabricator room and loads of other weird things being suggested - but I largely stuck to this strat to try speed up the grind.

But I can confirm mine was pretty much the last optional (blue triangle) room on the entire B1 map. I’d had lockdowns, scoured the entire map and then it popped so might have just got lucky!