Trapped in simalcrum

After doing wave 5 or 6? ( third change of the area) of simalcrum and exiting the area to the start , the door closed and there is no way to continue as all ways are cut off. Quite infuriating as i lost another key just before due to a crash.

Edit : I might have used blink to go back to the starting area

Anyone else had this happen?

Whup Whup
Here we go again