Apple delays HomePod until Early 2018

Apple just released a statement about the upcoming HomePod:

We can’t wait for people to experience HomePod, Apple’s breakthrough wireless speaker for the home, but we need a little more time before it’s ready for our customers. We’ll start shipping in the US, UK and Australia in early 2018.

Originally scheduled for December this means Apple will miss the upcoming holidays. The question is why did Apple announce it so early, in June 2017, even with a supposed launch in December. Did they run into issues with the production, the hardware or software itself?