Breach Astrolabe Autofails in Underground Sea

First full Poe1 League for me, going great. Accidentally opened an Underground Sea map instead of Dunes while farming Breaches with the Astrolabe. The boss room is too small to keep spawning monsters within the Breach area, so the progress bar stopped half way and when the Breach ended itself it auto failed the area.

I'm not sure if this is intended or not because I can just not have opened that Breach, either way, thanks if it gets fixed!