If you open a chat from wordpress.com/help/contact and then need to refresh for any reason or accidentally navigate away the chat is not reopened when you return and instead you have to navigate back to /help/contact and start a new chat.
It seems like we should automatically reopen Happychat if they have a recent session. I think this might explain the increase in user has left messages following our switch.
I found that in Mac + Safari this also occurs if you close the tab which has the chat open.
Steps to reproduce:
Result: the user will have closed the tab with the open chat, and the chat operator will see that the user has ended the chat.
Transcript: https://mc.a8c.com/support-stats/feedback/chat-transcript-hc.php?id=102348
Important Note: If, as a user, you are chatting with an operator and you have multiple WordPress.com tabs open for the same admin area (very common), only one tab in Safari presents the open and ongoing chat. If you close that tab, you end the chat.
An example situation: User has multiple tabs open of their admin, but sees our chat in their Customizer tab. Operator helps them resolve their question in the Customizer. Awesome! User closes Customizer tab (instead of clicking the X in top-left corner). User has left the chat, and the operator sees that the user has ended the chat.
This is being addressed in #10903
@beaucollins Can/should we add a confirmation dialog like when you have unsaved changes if the user tries to close the tab or navigate away with an active chat?
We could try it. My feeling is that we can instead keep the chat sidebar open after reloading and keep their typed message stored as well.
I think a confirmation dialogue would be great. Was just mentioning to Kris that I seem to be getting quite a lot of "user ended the chat" as _soon_ as they ask a question, which makes me think they're just clicking around all over trying to figure out their issue and didn't expect to lose the chat.
Or that. :P
I think lets see how common this seems to be happening after adding the sound notifications, visual notification, and fixing the /themes and Plugins section links to open in a new tab and confirmation dialog can be considered then if it still seems to be an issue
Sharing here an user feedback about this, if it helps:

He sent this after leaving the chat a couple times.