I was trying to build a large building near my base in creative mode, when I had the issue while trying to apply a wall to a ceiling (the technique where you build your floors by putting ceilings on pillers, then a line of walls around the edge below the ceiling)
Then after trying over and over to fix it and getting nothing, I realised I also couldn’t place a wall above the ceiling either… I then tested it by extending the piller into the sky, and building a tower of ceilings on that one spot, and no matter how high I go, I couldn’t build a wall on that one spot…
AND THEN IT GOT WORSE!
I tested if it was just that one spot, and it wasn’t. I ended up building a wall of piller by extending the ceiling tiles till I’d run into the bug again, then try to get past it (in other words, by going south 3, finding I can’t build a 4th tile south, so I’d build another tile east, then try again with South until I was able to build another in that direction) and found the bug just kept happening all over.
And there’s no reason for the game to have issues. I have collision off so I can build anywhere, so my building blocks will happily build into cliff faces or in villages, and the current location was a massive open flat zone.
Looking online, it seems like this has been a huge issue for over 5 years, yet it still hasn’t been fixed, or even explained why it happens?!