Manually placed Jigsaw blocks won't work correctly

I've noticed manually activated Jigsaw blocks doesn't work correctly, generating the next jigsaw one block below the original and choosing a random direction to generate, disrespecting the intended way "><".

 

The first picture is the manually placed jigsaw, and the second is the result.

 

Note: this only happens with the first jigsaw, the one you manually activate.

 

Note 2: I just reposted this as using Optifine is considered "invalid" by Moderators. This time the environment is Vanilla.