Azure: Adding routes to route tables using Service Tags fail with CIDR error

At current client we were deploying some API Management service resources yesterday. For this we needed a direct route to the internet for management and monitoring services for the setup to function properly. This can be achieved by using Service Tags. The two service tags used are: ApiManagement and AzureMonitor.

It worked fine to add the routes to the route table using the Azure Portal. However, when trying to push the same via ARM templates I got an error from Azure DevOps stating the following (also see screenshot below):

"AzureMonitor of resource /subscriptions/XXX/resourceGroups/XXX/providers/Microsoft.Network/routeTables/udr-XXX-001/routes/AzureMonitor is not formatted correctly. It should follow CIDR notation, for example 10.0.0.0/24."

It turns out that the API version of the route table resource in the ARM template was using a too old apiVersion. When updating the apiVersion to the latest one, it works (not for template itself but specifically for the resource, see below (initially a 2017-08-01 version was used):