I was in creative, holding a leash. I had 3 snow golems (they happen to be invincible, because I NBT edited them, but this was the only thing I did externally) . They were tied to a fence, but the leads and its knot became invisible (yes, another reported issue). I broke the fence, and was able to leash 2 of them but not the third. After the world was reloaded, it was fixed mysteriously.
EDIT:I'm in 14w25b and I feel like I'm experiencing a similar issue. I have two of the golems I had previously, and I put leashes on both of them successfully. When I clicked on a Nether brick fence, however, only one leash attached and I was left holding a leash. I swing like I'm placing the leash, but it doesn't actually attach. When I unleash and releash the golem, it still can't be attached. I can also stretch the leash line waaaaaay too far and the golem is not affected. This time, after reloading the world, the leash was attached to the fence.
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been delivered.