E.g. Sessions page pagination is set to 100. Auto refresh is 60 seconds. There are 120 online sessions and administator goes to the second page to see those last 20 sessions. After a 10 seconds 40 sessions goes offline (so only 80 should be showing). Sessions page auto refreshes and shows nothing. No pagination, no online sessions. Only the counter on the top shows 80. It should jump to the previous page automatically if there are no online session on the current page.
I ran into this as well I believe the attached patch against trunk fixes it. Will assign to 3.6.0
Of course, my patch has a bug when no users are logged in. $start becomes negative. reworking patch
reworked patch to avoid ISE when there are zero sessions.