If a scheduled task is in a running state (like waiting), and the associated endpoint records are deleted, the scheduled task becomes stuck and cannot be deleted
I've had the same issue. I've talked with support and I ended up just deleting from the database. Hopefully in future releases something is done, if possible.
The tasks are buried in multiple tables. It took me a while but I found most(if not all) of the dependents
Find the tasks
Get the number and place it in LD_Task_IDN. After deleted, you should be able to remove tasks.
Hope this helps in the meantime
Retrieving data ...