Hi,
After a bit of digging I have determined that Pushover is working the way it is setup to work. The test notification is sent out as a 'normal' notification with a low priority of -1 as shown in the \flash\config\plugins\dynamix\notifications\agents\Pushover.sh file:
MESSAGE=$(echo -e "$MESSAGE")
case "$IMPORTANCE" in
'normal' )
PRIORITY="-1"
;;
'warning' )
PRIORITY="0"
;;
'alert' )
PRIORITY="1"
;;
esac
curl -s -k \
-F "token=$APP_TOKEN" \
-F "user=$USER_KEY" \
-F "message=$MESSAGE" \
-F "timestamp=$TIMESTAMP" \
-F "priority=$PRIORITY" \
-F "html=1" \
https://api.pushover.net/1/messages.json 2>&1
From pushover.net
In order to verify that Pushover will generate sounds when there are higher priority notifications sent, I changed the 'normal' priority to 0 and then 1 and sent the test notification again. Each time my Android device generated the expected sounds.
Hope this helps anyone that may have been experiencing the same (non) issue that I was.