Help with indoors/outdoors

Any idea why this expansion of the garage I did is considered as "outside". It's completly closed and I checked for pilars but there is none. From the outside I can see inside the garage and the temperature is considered as "outside" even though I'm inside.

Also, note in the second image, there is like a "ghost" wall by the medkits, why is it still there if I already destroyed it with the sledgehammer?

Part of the expansion to the garage I did (outside)

The garage (inside)

Seeing inside the garage