I have noticed an issue when I have been upgrading all my hosts to 188.8.131.52. I have verified the same issue in the 184.108.40.206 viewer and my old 220.127.116.11 viewer version as well. When you attempt to use the right-click menu for 'Logoff' and you have more than 1 host selected, it does not action all your selected hosts - i.e., it does not log them all off. In fact - it seems to consistently log only >half< of your selected list of hosts. So if your had 10 hosts logged on and selected them so they are highlighted, right-click and Logoff, only 5 would log off. If you again right-click and select Logoff only 3 would log off, and if you do it again it would only log off 1, etc.
Steps to reproduce the issue:
1. set view to 'Details' to show a table list of hosts
2. Ensure you have Options|View and the setting 'Use Group View (< 1000 items) ticked
3. Select a number of hosts and set them to 'Logon' and they turn green and move to the 'Logged on) group.
4. Select all the Logged on hosts and right-click on them and select 'Log off'
5. Observe behaviour.