Issue with external monitor using curl on ntlm site

I need to create a monitor for our share point environment.

I first tried with the built-in HTTPS monitor, but it gave a 401 error. After some investigation it seems there is an issue if the service is using NTLM and I was recommended to use an external monitor.

With the information I found here I created the following script:

!/bin/sh

 This script expects the following Name/Value pairs:
  URI  = the URI to check
  USER = username
  PASSWORD = password
  RECV = the expected response (case sensitive)
 remove IPv&/IPv4 compatibility prefix (LTM passes addresses in IPv6 format)
IP=`echo ${1} | sed 's/::ffff://'`
PORT=${2}

PIDFILE="/var/run/`basename ${0}`.${IP}_${PORT}.pid"
 kill of the last instance of this monitor if hung and log current pid
if [ -f $PIDFILE ]
then
  echo "EAV exceeded runtime needed to kill ${IP}:${PORT} $PIDFILE" | logger -p local0.error
  kill -9 `cat $PIDFILE` > /dev/null 2>&1
fi
echo "$$" > $PIDFILE
 send request and check for expected response
if [ $PORT -eq 443 ]
then
  curl -kfNS --ntlm --user ${USER}:${PASSWORD} https://${IP}${URI} | grep "${RECV}" 2>&1 > /dev/null
else
  curl -kfNS --ntlm --user ${USER}:${PASSWORD} http://${IP}:${PORT}${URI} | grep "${RECV}" 2>&1 > /dev/null
fi

 mark node UP if expected response was received
if [ $? -eq 0 ]
then
   Remove the PID file
  rm -f $PIDFILE
  echo "UP"
else
   Remove the PID file
  rm -f $PIDFILE
fi
exit

Currently only using 443 so it on it will only use the first curl command, but wanted it able to handle both and I had some issue when I tried to use the second command.

The curl command works fine from the F5 cli and if I use "run /util test-monitor intranet_sharepoint_monitor_ext address 10.xxx.xxx.xxx port 443" from tmsh it correctly marks the nodes as up or down.

If do the test from the LTM Monitor I get "No successful responses received before deadline" if I try it on the share point that uses NTLM, if I try it on another share point that doesn't use NTLM it works fine.

Why would it work with the test-monitor command but not with the actual monitor in the GUI, shouldn't they be the same?!

Anyone have any suggestions on what I could do to solve this?

Have checked so it doesn't contain any windows characters and I have checked so that file located in /config/filestore/files_d/Common_d/external_monitor_d/ has the correct permissions.