One issue is that your redirections are in the wrong order

$ ( echo "out"; echo "err" >&2 ) 2>&1 1>/dev/null
err
$ ( echo "out"; echo "err" >&2 ) 1>/dev/null 2>&1
$
[download]

The first one, like you have, ends up redirecting stdout to /dev/null, but stderr to the original stdout. The second one redirects stdout to /dev/null, and then stderr to the new stdout, i.e. also /dev/null