Please clear push in Shell using the following command while logged in as SU:
push_remove list | grep -v Push | sed -e s/\ /\\n/g | xargs push_remove
Please restart the XMPP service in Monit Service Manager, the icon is located at the top right corner of the PBX WMS interface, a little circle with "i"
If the issue reoccurs you can:
Disable "Web push" in Collaboration settings -> "Personal"