I had a weird experience where I got raided and they made it up to the 3rd floor. My first cupboard was on the 1st floor walled in, with a second cupboard on the 3rd floor.
The raiders appeared to have destroyed walls to get up to the 3rd floor but then stopped. My 1st floor cupboard was still walled in when I woke up, unscathed, on the 4th floor.
Later on, another player said he used my bust open 1st floor to hide in, and authorised himself on the cupboard which was open to the air.
So it seems like someone walled in my cupboard later on with the idea that they could access my base at a later time.
So, what I really don’t get, is why the raiders stopped at the 3rd floor. If what you are saying is true and the gained priority by accessing my 1st floor cupboard, then surely they could have gotten through all the floors???
Very strange experience!