I never knew this was a real thing math people studied! I wonder if Douglas Adams knew about it when he wrote about the sofa stuck in the staircase in Dirk Gently's Holistic Detective Agency, or if it's a coincidence.
The reason was that the furniture was brought upstairs for the staircase remodeling, and the new staircase made it impossible to move it back.
I can believe it though as I had the same thing happen to me - I believe in my case the building had settled (it was always very wonky) and the sofa had sagged taking the result beyond the very narrow threshold that had let me get it in in the first place. A friend helped me saw it in half in the end after I dissuaded him from chucking it out the window; I was on the 8th floor and there were cars parked below so it would have been risky at best.
I'd always assumed the Dirk Gently story had inspired the maths problem, but I see from the Wikipedia article that it first arose in 1966 - so TIL.