As per the documentation, if you have manually provisioned the VMs (not from the Marketplace) you will have to manually upgrade the Azure VM agents:
Upgrade the VM Agent
The Azure VM Agent for Windows is automatically upgraded on images deployed from the Azure marketplace. As new VMs are deployed to Azure, they receive the latest VM agent at VM provision time. If you have installed the agent manually or are deploying custom VM images you will need to manually update to include the new VM agent at image creation time.
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