While trying to reproduce a suspected bug where the dragger (tragically) kills all of the welds in a model, I found that dragging a part with an orientation with components in these ranges 0, 120-150, 41-49
can break the CFrame and cause NaN and rendering issues.
To reproduce, drag this part or model with the new beta draggers enabled. Do not use the tool handles. Nothing is obviously wrong with any of the parts, just this problematic orientation. This was found by playing with a model welded together in an A>B>C pattern, but the welds are not necessary to cause this.
NaN.rbxl (18.0 KB)
Parts have properties that look like this when dragged, however the nearby parts that have gone invisible are perfectly fine despite not rendering. I think this is just a side effect of the invalid part being in the same chunk as other parts - instancing maybe?