Worked it out - trick is to open Settings. The Global/Home button also won’t go away till you open Settings, and in fact is occluding the reply text area as I type. So please excuse any typos - I can’t see the leftmost 15%.
Oh weird, it went back behind the keyboard once I dismissed and resummoned in an attempt to be able to hit the Reply button. Attempt successful. (Upload button still short here too. Silly buttons.)