Livechat Online-state depends on single agent not all agents

Description

It appears that livechat guests remains bound to their agent forever.

Pre-Condition

  • Agents are available and online
  • The single agent a livechat guest previously chatted with, is offline.
  • That old chat is marked as closed in omnichannel (and indeed was even deleted)

Problem

To that guest and only to that guest:

  • the chat-icon will be greyed out
  • the offline-form will be displayed.

Expectation

Instead I would expect

  • the livechat is shown as useable (no offline-form)
  • the new chat is routed to an available agent
  • optionally: give the guest the option to connect to a new agent.

Server Setup Information

  • Version of Rocket.Chat Server: 3.12
  • Operating System: GNU/Linux Ubuntu Focal
  • Deployment Method: tar
  • Number of Running Instances: 1
  • NodeJS Version: v12.21.0
  • MongoDB Version: 4.0.23
  • Proxy: nginx
  • Firewalls involved: none

Anybody experienced this?

I was not able to find a setting that influences this behaviour?
Have i overlooked something?

Asking here first, before opening a bug on github.