Thank you for your hint. I had 57 pending jobs and that helped me to release the jobs out of the queue! 
There is an open ticket about the issue on GitHub and a fix in progress:
With v5.12.25-M175, I still have to run the jobs manually to get rid of the pending jobs message:
2 Likes
louwerj
23
The solution works here too. The queue is empty again. Thanks!