Divide in Illustrator not producing the correct effect

While trying to get some practice with making geometric patterns in Illustrator I've run into an issue with the divide tool where illustrator is not producing the correct result. Here's my setup up, followed by the resulting shape that's created.

This is what should be produced through this result: 6 identical shapes (image stolen from a guide I'm following).

What am I doing wrong? I've done this in the past and it's worked but now it's not giving the same result. Tried restarting comp and CC and yet nothing.

Thank you for reading.