How far from absolut origin are you modelling your project? How far is your project origin from absolut ArchiCAD origin?
If you are too many kilometers or too many miles away from AC absolut origin, things like this might start to appear.
The fix would be to move everything closer to AC absolut origin. You could do it with a double marquee in 2D plan, and with everything unlocked, and every layer opened and and unlocked, and with all the renovation options available and opened up. Be carefull with all of these, to not mess up your model too much.