Enter stops working when replying to SMS on iPad in both Safari and Chrome.

This is an incredibly vexing problem which occurs whether using Safari or Chrome on my iPad Air 2. Everything appears to be sweetness and light while replying to SMS: I hit the enter key and the response is sent. After a couple of hours of now problem the enter key does a carriage return and stops sending the message.. Pressing the send button doesn't work. I log out on Safari and immediately log in on Chrome: same problem. This happens regardless of which browser I start with. A couple of hours go by, I try again with either browser and we're back to sweetness and light: hitting enter sends the message, consistently until after a while the problem resumes. Please advise, I really need help. Thank you! Ivan.

Should it be possible that the Enter button is hidden by the status bar?
Like this: