Usually the first thing to check is whether there are any sessions that show a status of things like Pending/Running/Warning/Stopping (I think that's it hmm). Most of those states you can filter directly on (except Warning I think). You'll also want to increase the Filter on column on Start Time to some time in the past.
It's possible there's some pending/running session lock in the DB, but usually that isn't the issue. I would check the simple stuff first just by increasing the filters to include more time.
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Dave Morris
Cano Ai
Atlanta, GA
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Dave Morris, 3Ci at Southern Company