uPyCraft editor not showing text

The editor in uPyCraft on my Mac is behaving strangely. When I paste the text of an example program into it, I don’t see the text.    Rather, I see the last few characters in the last line in the program repeated at each line of the code.  (For example, a 10-line program will show me 10 identical lines – each of which is the last few characters in the last line of the program)The program seems to execute fine and can be loaded onto my ESP32.  However, editing is impossible because you can’t see the lines of text.   Ant ideas?