@Denis__Dennehy, the schedule included only one Run-time Resource on which multiple processes were to be triggered sequentially. The knowledge article mentioned by you should not possibly be the reason why this issue might have occurred, since the Resource had been 'Connected' and only due to which it could create a pending session.
Also, the scheduler never failed. It was still in the running state with blue play icon and the status did not change until the pending session was deleted.
After the session was deleted, the logs were inaccessible. When I had checked the logs before deleting the session, it indicated that it was on the 'Set Windows Login' process and had been like that for hours.
Can anyone provide any more details on that?