Hi Scott Klein,
Welcome to Microsoft Q&A forum.
As I understand, you are getting "Could not connect to master" error in Azure Elastic Job.
This error could mean that the Elastic Job Agent cannot connect to the target server(s) because the target has some firewall rules blocking the connection requests. Indeed - it is required that every target in the target group allows connections from Azure Services in order for Elastic Jobs to work. To fix this, I go to the target server in the Azure Portal and click on the “Firewalls and virtual networks” item under “Security”. Next, I toggle the "Allow Azure services" from OFF to ON and save my changes.
Please look at the other troubleshooting options given here: https://techcommunity.microsoft.com/t5/azure-sql-blog/troubleshooting-common-issues-with-elastic-jobs-in-azure-sql/ba-p/1180766
Also, please recheck credential, permission and network aspects once again.
Let us know if this helps and share your observation.
Thanks