Experiment was launched and the job was submitted to Slurm cluster. After nearly 4 hours the user sends a cancel request as the job was queued for a long time. The cancel request has come on the same day but it didnt process it. Hence the experiment was left as CANCELING without processing and cancelling it.
This issue was seeing occurring in multiple HPC clusters with the gateway.
NOTE: the email shows that this was queued for nearly a day but no indication of job completing email in the mailbox.