I’ve had to rebuild about 20% of the house from the bottom up, because one of the foundations glitched out and showed only “red stability” despite being on the lowest level on even ground.
Those Stable Pieces (with pillars and opening) Do not have connect points like other pieces.
It was brought up when Stable parts came out, (really hard to make proper stables, since they offer no support(stablity?) They’ve never come back to them to fix it.
You need other pieces around it for stability, I tend to break few other parts down, or find way to add wall some else. Sucks cause it’ll work one side, by time you get to other end, how math works out, it’ll never have enough.