Hi!
I've had this going on for a while. It seems to be an intermittent problem when on my Android phone. I haven't experienced it with any other sites or apps.
The problem is when I want to go back and edit text in the message box. Even though the cursor seems to be flashing in the right place, as soon as I enter text or new line or whatever, this is entered at the end, wherever the cursor was previously. However, if I put the cursor in the middle of a word, then it works.
It's making editing posts difficult as I usually have to delete whole chunks of text to make changes further in.
Hope this makes sense.