Iron bars don't use connected textures, but they're affected by the same annoying issue where culling doesn't work vertically. It's the same problem (https://bugs.mojang.com/browse/MC-50349), and can be "fixed" (disregarding the side effects detailed in #74) in the same way.

For iron bars specifically, this broke in 1.8 - it was fine in 1.7 and earlier. Here's a comparison:

Custom culling behavior is not something Continuity deals with. There may be other mods that allow this.