With the simple example shown I get Error message 707:
"Cannot open file/storage/emulated/0/My Documents/Pictures/app_inventor_16583507404025.png"
This example was displaying a qr code and then stopper working. I reinstalled the extension and the ai2 companion and restarted my phone, all with no improvement. It seems as if the extension is not able to write to the phone storage system.
Thanks for everyone's help. The problem has been solved. The issue was that the path identified in the Error message could not be found. The extension I used has the storage location hard coded into it and does not allow the user to change it. This path was missing from my phone. I solved the problem by creating the missing path using a file management app.