When trying to place a curved rail, if it is blocked by something under the straight edge, the rail will turn red, but the obstructing item's hitbox isn't highlighted.
See pictures:
vs:
The rail is only moved one block up, so it collides with the tree not on the edge.
[0.11.15] Curved rail not showing collision box on edge
Re: [0.11.15] Curved rail not showing collision box on edge
Yes. I also noticed this.
Re: [0.11.15] Curved rail not showing collision box on edge
Thanks for the notice, it is fixed for 0.11.16 now.