sshpass bash not working well

I have a problem with a bash script.

#!/bin/bash
USERNAME=pi
HOSTS="192.168.1.21 192.168.1.22 192.168.1.23 192.168.1.24 192.168.1.25 192.168.1.26 
192.168.1.27 192.168.1.28 192.168.1.29"

SCRIPT="pwomxplayer -A udp://239.0.1.23:1234?buffer_size=1200000B"
for HOSTNAME in ${HOSTS} ; do
   sshpass -p 'Nasanasa0401' ssh -o StrictHostKeyChecking=no -l ${USERNAME} ${HOSTNAME} "${SCRIPT}"
done

The problem is that it takes a long time to execute the command in the following ip and when I look at the services on the raspberry pi master where the bash is running I notice that I have two services running and one says zzzzzzzzzz

Does anyone realize that I may be doing wrong?

The following attempt works fine:

#!/bin/bash
USERNAME=pi
HOSTS="192.168.1.21 192.168.1.22 192.168.1.23 192.168.1.24 192.168.1.25 192.168.1.26 
192.168.1.27 192.168.1.28 192.168.1.29"
SCRIPT="sudo killall pwomxplayer.bin"
for HOSTNAME in ${HOSTS} ; do
   sshpass -p Nasanasa0401  ssh -o StrictHostKeyChecking=no  -l ${USERNAME} ${HOSTNAME} "${SCRIPT}"
done