Fences are connecting to non-full blocks

While playing in creative mode, I came across a mineshaft. I was surprised to see the fences were incorrectly connecting to the rails. I broke and replaced the rail, with the same result. I experimented with a few other placeable items, but not all. The following are blocks i tested, but im sure there will be others I did not test; levers, torches (rs and light), vines, tripwire hooks. I did try with ladders but the fence did not connect to these I also tried placing these items around cobblestone walls, glass, and iron bars, and they all connected in the same way.