I’m not sure, but this might not be a bug. I remember something like they allowed this behaviour to avoid that settlers get stuck inside unfinished houses.
Although we’ve seen this issue long before…
Are you referring to real flying? Like going from one wall to the opposite one levitating? Then it could be that you had the roof hidden in the sight mode.
And yes, try to reproduce it, it will be really helpful 
Edit: was it something like this?