Chats do not appear until the page is refreshed

[ececec]

Some agents are reporting that they are not being alerted to new chats, even though they have been logged in all day, but when they refresh the Live Chats page the new chats appear.

Report from an agent:

I have been on webchat all day today, this afternoon we had 6 logged in.
One of my colleagues happened to say he had 2 webchats on the go. I checked the page and it was showing none as did my colleagues. Only when I refreshed the page did it then show the 2 chats and notifications then popped up.
It appears that if you do not regularly refresh the page any new chats don’t show.

I also had this message from an agent:

There was a point where one colleague had 2 chats at once and then as he was flicking between the 2 the text writing disappeared on both. He logged out and back in again and the chats had gone.

Version 9.0.23

The plugin is working fine for me when I tested it, the agents in question are all behind a different firewall on a different network to myself and also use Chrome on Windows machines, while I use Chrome on a Mac.