Sorry for a delay and thank you very much for the question.
There is a special "Veeam Backup: Job RPO Compliance" Monitor which will alert if Job is running beyond the configured timeframe. This monitor is disabled by default because it should be configured with the desired RPO threshold (a threshold for how much time your replica could be unsyncronized). You can get some additional details in the Backup and Replication MP Guidehttps://helpcenter.veeam.com/mp/80/backup_guide/index.html?veeam_br_job.html
But as a QuickStart Guide - just enable it for your replication Jobs (or a single job) and set RPO to 24-25 hours for example, so that it will alert if Job is running longer than on the previsous day.
Let me know if you have any additional question about using this monitor.