варианты из документации:
No recommendation - Reasons that can cause a VM not to be recommended are:
Missing NSG - The just-in-time solution requires an NSG to be in place.
Classic VM - Security Center just-in-time VM access currently supports only VMs deployed through Azure Resource Manager. A classic deployment is not supported by the just-in-time solution.
Other - A VM is in this category if the just-in-time solution is turned off in the security policy of the subscription or the resource group, or that the VM is missing a public IP and doesn't have an NSG in place.