Why did yesterday's OnePlus 6T update break Messages?

geoffarnold

    My daughter and I have new OnePlus 6Ts. We use Messages a lot to exchange long (multi-segment) SMS messages. Yesterday we both got the latest update pushed from T-Mobile, with a description that indicated that RCS fixes were included. On restarting, I now find that Messages won't let me compose a message longer than 1000 characters. Meanwhile, my daughter is limited to 100 characters!

     

    What's going on? I checked with OnePlus: they have no idea. (The phones were bought from T-Mobile.)