Random destructible meshes despawning

I’m new to game development, and I’m mostly messing around. I’m trying to create a building with destructible walls, and floors. None of these walls are overlapping, but some of them disappear when shot, and it’s not always the same ones either. (the projectiles have been changed to a small cone, so they’re not really visible) unity destructible items disappearing - YouTube

to make this, I followed these instructions - How to shoot through walls unreal engine (tutorial) - YouTube

Sometimes they will dislodge instead. (I also would like it if pieces still touching something supported would not fall, is that doable?)