the plugin is using the Rubrik API, but if you query for a single backup job it could take minutes to complete in a bigger environment with a lot of backup jobs. if you are using curl and the API with a query object that is using a job name, the query finish within 1-2 seconds.

curl -H "content-type:application/json" -H "authorization: Bearer xxxxxxxxx" -H "accept:application/json" 'https://xxxxxx.xxxx.com/api/v1/job_monitoring?limit=500&object_name=my-backup-job-name' | jq

looks like the plugin is receiving the whole jobs list and than doing a selection, this could be optimized by building the query URL like in the curl command, so you receive very fast the result and have not to wait minutes (timeout of the check and the centengine default timeout is too low)