It’s not really a bug. There is no 100% correct way to sort transparent objects so that they work correctly. I can prove it with just two triangles.
In some case, you can trick sorting to always be correct for a particular set of geometry by forcing a fixed order. For example, always rendering the inside of a transparent cube before the outside. Or in your case, always rendering the floor before rendering the columns.
…but sometimes this isn’t even enough if the scene is more dynamic and you start to realize why games don’t have that many transparent objects in them.
This article talks about why the z-buffer is both friend and enemy in these cases: