Since upgrading from 2016.3 to 2017.1, tasks seem to hang and lock with only one or two active devices. This for Push of Policy-supported push tasks. When I right click the task there is no option to Cancel, Delete or Start Now. The job does not time out and stays active indefinitely even though the "Default scheduled task settings" have a "Maximum task run time" of 120 Minutes.
The only way to cancel the task is to restart the Scheduler Service which then kills all my running tasks. This was not an issue with 2016.3.
This is most likely a fault of some kind with the scheduler service itself, as opposed to a defect in the 2017.1 product. After your upgrade, did you reconfigure the account for the scheduler service? Are you able to control (start and stop) the service successfully?