Opening a door of a spacecraft or building inside an unbreathable atmosphere does not turn air unbreatable, not even in roomvoids with the same name as a roomvoid next to a hull void or the outside.
In space the loss of pressure still works fine however, in the same ship design. The helmet indicator turns red a while after you open the door, as it should.
And yes I'm sure the planet has unbreathable atmosphere, because as soon as I leave the exposed room, the helmet indicator does turn red.
I noticed this quite a while ago for buildings, but didn't notice it happening in spacecraft until today (haven't payed attention to it), so no idea which update might have caused it.
In space the loss of pressure still works fine however, in the same ship design. The helmet indicator turns red a while after you open the door, as it should.
And yes I'm sure the planet has unbreathable atmosphere, because as soon as I leave the exposed room, the helmet indicator does turn red.
I noticed this quite a while ago for buildings, but didn't notice it happening in spacecraft until today (haven't payed attention to it), so no idea which update might have caused it.