This can be replicated in following scenario:
1. Launch Citrix session with a multisession VDA
2. Disconnect the session
3. Reconnect to the session, session is showing as disconnected on the Studio and Monitor but is active on the VDA.
4. If user disconnect the session again, session is terminated on Studio and Monitor, however, it remains disconnected on the VDA. User will not be able to reconnect to the session again.
5. If user attempts to reconnect, a new session is brokered.
On the VDA user will have two sessions, one active and one disconnected.
Note: Issue only appears on multisession OS
User Configuration\Administrative Templates\System\Ctrl+Alt+Del Options\Remove Lock Computer
Policy setting "Remove Lock Computer" is enabled