Issue with CollapsingToolbarLayout title and design 25

We recently upgraded the design library to 25.0.1 to give the new bottom navigation a crack. This broke some existing functionality we had for the CollapsingToolbarLayout:

This took a while to find, but using the famous Cheesesquare example from Chris Banes as a reference, I was able to narrow it down to not adding a setSupportActionBar(R.id.toolbar) to my activity (for which we didn’t require at the time). Hopefully it can save you a bit of time if you have encountered the same issue!