Just did the new update. Went and chatted with neighbors and the chat screen went down to about 1/4 useable. The other 3/4 remains blank. I closed the hayday app, closed it from running in the background and restarted it. Started reading the chats and it was back to being a full screen. I tapped to open the keyboard and it went back to 1/4.
Playing on a Samsung Galaxy note 8.
Edit:
Also just noticed that going to the fishing pond triggers the partial chat screen.