I'm hearing reports that layouts don't appear on some devices under the latest iOS 13 update. It looks like this occurs when no value is set for Settings > Appearance > Color Theme, which causes a problem with the new iOS 13 Dark Mode option. Setting any value for Color Theme within the app should fix that. The next app version, now in Apple's review queue, will set a default value on any devices where it is still not set.
The new app version 6.0.7 is now available for download.