Sending a message in the app's Team chat failed every time with "Check the fields and try again." The app always sends an empty file-attachment list with a message, and the server rejected that list as if it were text. Sending now works again, including plain text, photos, voice notes and files.
On a channel with no messages yet, the "No messages yet." note appeared upside down. It now reads normally.
These changes apply to the mobile development app; native device testing is still required.