These were URL scan "update" queues. Only 1 queue worker for that queue can be running at a time, and it looks like the previous one had "died". I reset the queue worker and they have all processed.
You can do this yourself if you see this again - from that screen:
1) Click on "View Entries"
2) Click on "Reset" for the entry in the last that is being worked - you'll see it has a worker assigned to it.
That will reset that one and get the queue moving. You really should almost never see this though - if you see this again, it could indicate there is an issue that is causing the process to bomb out and not complete the queue entry.
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Brian Johnson
Founder and Lead Developer - Jamroom
https://www.jamroom.net